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间谍vs汗水:有关中国核进展的辩论   

2016-02-01 15:46:10|  分类: 核武器 |  标签: |举报 |字号 订阅

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〔美〕布罗德
《纽约时报》,1999年9月7日

当美国核弹制造者于1979年开始访问中国时,他们对越来越一针见血的提问感到吃惊。这些提问表明,他们的中国同行强烈希望探索建立一个现代核武库的秘密。这种秘密能使氢弹制造得如此之小,以致许多弹头能安装在一枚导弹上,或者从卡车、潜艇或其他机动平台上发射。
中国于1992年9月25日获得了成功。这个消息来自一名间谍,他告诉其美国联络人,北京爆炸了一颗基于小型化秘密的核弹。位于新墨西哥州的洛斯阿拉莫斯武器实验室的一个科学家小组开始了关系重大的调查工作:中国的进步是间谍活动的结果,还是艰苦工作的结果,或者是两者兼而有之?
这场辩论如今仍在激烈地进行。专家们一致认为,发生了间谍活动。但是,究竟有多少秘密被窃,如果有任何秘密被窃,被窃秘密对北京的进步产生了什么影响—在这些问题上的分歧很大。
洛斯阿拉莫斯小组于1995年得出结论认为中国的飞速进步或许是以间谍活动为基础的。今年一个国会委员会的使这个案件变得公开的报告走得更远,声称“没有窃自美国的核机密”,中国“事实上不可能”造出小型弹头。
这份国会报告引起政府内外科学家们的批评。他们说,间谍活动的重要性被夸大了,而正如中国所公开坚持认为的那样,中国很可能是自力更生实现突破的。
一项对这种争执的评述是以为期数月的采访以及揭露武器和情报工作的机密为基础的。这项评述表明,在坚称窃得的机密是中国实现突破的主要原因方面,国会的报告是没有证据的。
这项评述也支持正在争论不休的专家们中间逐渐形成的一个共同观点:联邦调查过早地把注意力集中于洛斯阿拉莫斯国家实验室以及那儿的一个名叫李文和的工作人员身上。他因违反保密规定已被开除。现在看来,分布在美国武器系统各部门的成百上千、或许是成千上万的人,都能获得丢失的机密。
联邦官员最近要求不公开有关武器设计和情报来源的某些细节,《纽约时报》同意不公开这类细节。
对洛斯阿拉莫斯的侦查小组来说,整个间谍理论在1995年得到强有力的支持,当时中央情报局获得一份中国内部文件。这份文件包括对美国最先进的小型弹头W-88的描述。联邦官员在首次透露其在这起案件中的最重要证据——这份中国文件的秘密内容时说,中国文件列举了这种弹头的5个关键特征,包括精确到不超过1英寸的4%的两种尺寸。
但是,批评者也透露了新的情报。他们坚持认为,即使北京进行了间谍活动,北京也是依靠自力更生完成小型化突破的,用了至少13年时间从事小型化研究,从1979年至1992年。
美国专家说,中国科学家的杰出才能从他们制造的照像机中可见一斑。他们为拍摄核爆炸而制造的这种照像机远远优于美国制造的类似照像机。
洛斯阿拉莫斯武器实验室前主任阿格纽(H. Agnew)说:他们不需要我们的任何帮助。他们只是好奇,就像我们对他们感到好奇一样。”阿格纽访问过中国,是联邦情报顾问。
解析间谍活动所造成的损害是一门不精确的技艺,这种解析是推理、求证和演绎兼而有之。在已知的和被怀疑的之间的真空地带,个人的、党派的或机构的偏见往往乘虚而入。
有关中国间谍活动的辩论被一系列问题玷污了。这些问题包括:共和党嫌恶克林顿总统的中国政策,对在调查中存在种族偏见的指责,以及科学家中间对这种喧嚣正在促使保密措施变得如此严厉,以致损害工作、士气和招聘的担心。
就像在大多数间谍案件中一样,对证据可作出多种解释。若干熟悉这份中央情报局所获得的中国文件的批评者说,这份文件对美国弹头的描述本身不足以造出小型化弹头。
监督洛斯阿拉莫斯调查的能源部官员特鲁洛克(N. Trulock)同意这种评估,但说,这种情报是秘密的,从来没有在任何公开文件或者因特网邮件中提到过。他及其小组推论,任何获得这种情报的人,必定也能获得范围更广泛得多的弹头设计秘密。
此外,特鲁洛克先生在接受采访时说,了解部件的近似体积和形态为中国炸弹制造者提供了一张路线图,或许使他们能节省数年初步试验的时间。
然则,特鲁洛克先生补充说,国会委员会在其报告中说得太绝对了。这份报告部分地是以他的证词为基础的。
能源部前情报主管特鲁洛克先生说:“我在作证时,为了表示我们的证据和我们的结论的不确定性,使用了适当的告诫性语言。我们一般说,`也许是这样,也许是那样。’”他说,该委员会对间谍活动在中国核突破中所具有的中心地位“作出了判断”。
加利附尼亚州共和党人、参议员考克斯(Ch. Cox)是这个委员会的主席,他为自己的47名工作人员工作成果辩护,而这些工作人员没有一个具有核设计经历。他在接受一次长时间的采访时说,这个专门小组多半把克林顿政府的证词作为其专家鉴定。他说,间谍活动使北京能节省数十年研究时间的结论是一个适当的结论,依据的是政府自己提供的证据。
他在对特鲁洛克先生的批评作出反应时说:“作出判断是重要的。我们不可能确切地了解每一件事。问题在于,更有可能的是什么。”
在接受这次采访时当被告知中国对小型化秘密的兴趣的深度和广度时,考克斯先生表示吃惊。他也对联邦政府中对中国间谍活动持怀疑态度者所提出的一种观点表示不以为然。这种观点认为,世界上大多数核大国都已解开小型化秘密。
考克斯先生问道,因为法国解开了小型化秘密,难道中国就能“自力更生做到这一点?这是一种歪曲。这几乎是把苹果和柑橘混为一谈”。

秘密:美国缩小了核引信

从核时代一开始起,小型化就困扰着武器设计者。
世界上的第一颗原子弹由洛斯阿拉莫斯实验室设计,于1945年7月在新墨西哥州沙漠中爆炸,是一件可怕而笨重的东西。一块垒球大小的钚被一个更大得多的装满烈性炸药的球体包裹着,这个球体的宽度达5英尺,使用了32料炸药和64个雷管。这颗原子弹与一辆汽车一般大,不可能装入一架小型飞机,更不必说安装在导弹上。
1952年,美国物理学家完成了一项重大突破:氢弹。氢弹的威力超过第一颗原子弹大约1000倍,是一种两级装置。在氢弹厚实的壳体内部,一次核爆炸——被称为初级爆炸——起引信的作用,点燃氢燃料的威力更强大的爆炸——被称为次级爆炸。
体积从一开始起就是一个问题。第一颗氢弹竖起来有两层楼高,重82吨。氢弹只有缩小体积,才能用于军事,在以后几年里,美国最优秀的物理学家们着手所做的正是这件事。经过很多次试验和失败,他们懂得了能从更小的弹体中获得同样性质的爆炸力。主要突破以大而笨重的核引信为中心。科学家们通过把核引信的钚燃料制成大致与西瓜一般大小的卵形,就能大大缩小引发核爆炸的炸药的体积和数量。
汉森(Ch. Hansen)写了一本描述美国早期核努力的详尽历史的书。根据他的说法,经过至少一次失败,1957年7月,这个激进想法在内华达沙漠进行的核爆炸中变成了事实。美国从造出第一颗氢弹到实现氢弹小型化用了5年多一点时间。
这种发展对冷战的核竞争来说具有深远的含义。
把核引爆装置从一台洗衣机那么大缩至比一个足球还小,这使武器设计者们能把热核武器放在能从潜艇或诸如卡车等机动平台发射的小型导弹上。热核武器的使用将不再受轰炸机或者地面发射井的限制。
这种进展意味着热核武器现在能被十分秘密地携带至更接近敌方海岸的地方,并更能免受攻击。这也意味着弹头能被放入鼻状圆锥体的狭窄空间。
锥形弹头能比钝形弹头更快速地飞向地而,并在燃烧冲刺期间较少受风力影响,从而使弹头变得更精确。
新一代热核武器的第一种弹头是W-47,其体积不及那颗把广岛夷为平地的原子弹的一半,但威力增加了50倍。1960年,当第一艘“北极星”潜艇出海时,其16枚导弹各携带一颗W-47弹头。
热核武器继续发展,而根据大家所说,W-88弹头于80年代问世使这种发展达到了最高潮。W-88是美国核武库中最致命的武器之一。
这种弹头是为潜艇制造的,10年前首次出海,被认为体积虽小但威力十分强大。弹头的确切体积是保密的。但是,一枚三叉戟D5导弹能携带至少8颗W-88,而这种导弹的直径不到7英尺。由于三叉戟潜艇能携带24枚导弹,一艘潜艇就能携带多达192颗这种热核武器弹头。如今在大西洋中巡逻的美国潜艇都携带这种小型弹头。而且,美国海军正在将这种弹头装备其太平洋舰队,因此,在未来几年内,W-88很可能把目标对准中国。

中国人:较晚起步,迅速超越

中国较晚加入核俱乐部,但在加入时显示出相当高的技能。
北京于1964年爆炸其第一颗原子弹。与投在广岛的那颗原子弹一样,这颗原子弹的设计是以铀为基础的,但节省了昂贵的燃料,而且造得更轻巧,增加了其军事价值。
斯坦福大学物理学家、克林顿政府顾问德雷尔(S.D. Drell)在《中国制造原子弹》(1988年)一书中,称中国的原子弹“给人留下非常深刻的印象”。仅仅32个月后,北京的第一颗氢弹就问世了。
自然资源保护委员会是华盛顿一个监督核武器的私人团体。该委员会的诺里斯(R.S. Norris)说,相比之下,从核武器发展到热核武器,伦敦用了66个月,莫斯科用了75个月,华盛顿用了78个月,而巴黎用了103个月。
中国仅进行6次试爆就达到了氢弹阶段,而美国进行了13次试爆。这种较低的数字是典型的。在发展至少6类核武器期间,北京在数十年间进行的核试验相对说来较少,总共才45次,而美国进行了1030次。
有证据强烈表明,中国在其制造导弹的第一阶段,不知如何缩小热核武器的体积。根据《中国的战略海军力星》(1994年)一书的说法,北京在70年代部署的潜艇导弹的弹头重1300磅,体积是美国旧式W-47型弹头的两倍多。这表明,中国人仍在使用球形核引信引爆氢弹。
中国陆军的核力量是不太强大的。从80年代开始,中国部署了大约20枚现在能到达北美任何地方的导弹。每枚导弹携带一颗爆炸力相当于500万吨烈性炸药的弹头。这种爆炸力比投在广岛的那颗原子弹强大约300倍。
大型弹头并不特别精确,但它们符合中国宣布的战争学说——只是作为报复发射核武器。大型导弹如有必要能袭击一座城市。
70年代末,美国一种精确度很高的设计的发展激起了中国对制造体积较小的核武器的兴趣。美国的这种设计以“实验导弹”或者“MX洲际导弹”著称,能携带10个分导核弹头。这种武器虽然主要是旨在使莫斯科感到不安,但也使北京感到担忧。北京迅速地懂得,其少量大型陆基导弹看上去就像是孵卵的鸭子,在精确制导氢弹的第一次打击中就可能被摧毁。
70年代末,当美国海军透露研制一种新的潜艇发射的导弹的计划后,北京的不安增强了。这种新的导弹几乎与MX洲际导弹一样精确,但携带威力更强大的弹头——W-88。
在尼克松总统于1972年访华之前美国情报机构对中国的核计划和现代化计划即使有所知情,也是知之甚少。但是,在尼克松的外交主动行动打开大门后美中两国建立了军事联系。
到1979年,美国的核武器设计者和安全专家开始造访其中国同行、武器实验室和罗布泊。罗布泊是中国西部沙漠中的一个辽阔地区,原型核武器就在那儿试爆。
根据中央情报局前官员弗鲁曼(R.S. Vrooman)的说法,从1979年至1990年,仅仅洛斯阿拉莫斯就有至少85名科学家和官员访华。弗鲁曼当时领导洛斯阿拉莫斯的反间谍工作。
最重要的访华人员包括洛斯阿拉莫斯武器实验室前主任阿格纽博士、该实验室情报主管斯蒂尔曼(DBtSilma)n以及后来成为里根总统的科学顾问的物理学家基沃思(G.A. Keyworth)。访华所带来的好处被认为远远超过武器科学家们在非正式场合和交谈中可能有意无意地泄露机密所造成的风险。而且,事实上,美国人获悉了很多情况。
一个以匿名为条件发表看法的美国官员说:“这对美国来说是一次规模极大的情报收集行动。一开始我们对中国一无所知。”
一个发现是,中国的部分计划是十分先进的,包括核弹研制技术。
在1979年和1982年是首批访问者之一的阿格纽博士说:“他们拥有精良的设施,一些设施比我们更先进。”
他说,例如,中国人能用一种被称为“皮内克斯”的先进照像机拍摄核爆炸,并把拍摄到的细节用于弹头研制。
他说,美国的同类设备只有一根轴,而中国的有两根轴,从而使其效用增加了一倍。阿格纽博士说:“中国的照像机更精良得多。”
美国访问者还了解到有关中国缺乏什么的很多情况。从多年间连珠炮似地询问显然可知,北京急于尽可能获悉与缩小核引爆装置有关的一切东西。美国官员说,中国人的提问是经常的,针对性越来越大,并且从来没有得到回答。他坚持认为,北京用这种方式没有获得秘密。
但是,在一个案件中,调查人员开始对加利福尼亚州利弗莫尔武器实验室的一个美国科学家产生怀疑。
这个科学家曾于1979年与中国科学家交谈过。这个出生于台湾的被怀疑者从未承认过。但是,在一次代号为“诱虎”的调查中,一些联邦调查人员担心,这个科学家不仅泄露了中子弹W-70的设计,而且泄露了制造小型核引爆装置的秘密。
武器专家说,有关西瓜形状的关键信息可通过寥寥几句评论、一个手势或画在信封背面的简单草图传递,虽然接着需要多年的计算、分析、试验和工厂劳动,才能把这种想法变成核爆炸。
洛斯阿拉莫斯国际安全研究室主任霍金斯(H.T. Hawkins)说:“真正的挑不是在于设计,而是在于制造。”他说,例如,钚是科学已知的最复杂的金属之一,因为它与其他金属和材料的奇特的反应方式,很难浇铸成型。
霍金斯先生在提到这种充当大多数核弹的燃料的高密度金属时说:“这是一头怪兽。”

突破:中国的核跃进

美国官员透露,中国最终于1992年9月25日成功地爆炸了一颗小型化核弹。情报分析家们花了两年多时间才充分了解到,中国取得了什么成就。只是在一个受雇为美国从事间谍活动的中国核专家向其美国上司送交一份吸引人的报告后,中国的这种成就才变得一清二楚。
这个间谍说,中国9月的核试验最初被美国分析家认为是常规试爆,但绝非常规试爆。这个间谍说,这天爆炸的核弹是小型化的,具有一个特殊卵形的中心部分。这表明,中国已开始掌握制造现代弹头的技术。
在90年代中期,追踪其他国家核计划的技术内情的任务落在国家武器实验室身上。追踪者之一是洛斯阿拉莫斯的经验丰富的武器设计者亨森(R.M. Henson)博士,他自1988年以来一直在分析有关外国核计划的情报。
亨森博士在接受来访时说,1955年1月,他开始更密切地考查中国是如何解决小型化难题的。他求助于专门分析俄罗斯核计划的朋友布思(L.A. Booth)。
他们起草了分析报告,最终把这份报告交给了前一年已成为能源部情报处长的特鲁洛克先生。他希望邀请其他核专家、尤其是在研究氢弹的小型化核引爆装置方而具有长期经验的核专家参与亨森博士的工作。洛斯阿拉莫斯符合这项条件的科学家里克特(J.L. Richter)加入了亨森博士的小组。官员们在一次新的透露中说,这个小组更仔细地考查了那个中国间谍提供的一条线索。那个中国间谍描述核弹的核中心部分的体积与一种常见的家庭用品相似。科学家们从这条线索着手,计算了更精确的体积,而亨森博士和里克特博士查遍美国核武器资料库,看看有什么核弹的中心部分的尺寸与此相符。
他们发现,W-88的核引爆装置在体积上接近得足以引起怀疑。
能源部举行了多次会议,中央情报局和国防部情报局的分析家与洛斯阿拉莫斯的小组一起出席了这些会议。联邦官员现在说,这两个情报机构持怀疑态度,并推论说,一个外国人的粗略类比被小题大作了。但能源部和洛斯阿拉莫斯的小组觉得,证据是发人深思的。
正如以前已经透露的,突破出现在1995年,当时一名中国政府官员把一包中国机密文件寄给了美国官员。
特鲁洛克先生说,最能透露内情的一份1988年的文件展示了北京的第一机械工业部的核现代化计划。第一机械工业部除了别的东西,还制造导弹和鼻状锥体。这份文件不仅描述了中国的计划,还把中国的计划与美国军械库中的核武器进行比较。
相对粗糙的手绘草图画出的鼻状锥体包括W-88、W-87、W-78、W-76、W-42和W-56——三叉戟导弹、MX洲际导弹和民兵导弹的弹头—还标出了它们的全部重量和体积。
这些草图本身不能导致定罪。尽管这种情报就官方来说在某些情况下仍是保密的,但当时通过许多不保密的美国文件和文章已能广泛地获得。
可是,联邦官员透露,这份经过翻译约有20页的中国文件继续提供了有关W-88的敏感资料。它精确地描述核引爆装置的形状不是球形的,并说,核引爆装置位于鼻状锥体狭窄的前部靠后的位置——这种安排用于美国的某些弹头,而不是全部弹头。而且,这份中国文件正确地描述氢燃料或称次级燃料具有球状。
更令洛斯阿拉莫斯的小组感到不安的是,这份中国文件所描述的包裹核引爆装置的外壳的宽度精确到了1毫米,即1英寸的4%。特鲁洛克先生回忆说:“真是精确极了。”
一名联邦高级官员同意这种说法。他说:“这使我们开了眼界。这份中国文件看来证实了早些时候看上去不可靠的评估。”
特鲁洛克先生说,他的小组后来发现,这份中国文件提供了W-88的次级或称氢级燃料的宽度的同样精确的尺寸。他在提到核引爆装置的重要性时说:“初级燃料就像支撑帐篷的长支杆。但这种尺寸与初级燃料的尺寸一样精确。”
中央情报局最终断定,寄来这些文件的那名特工是根据中国情报机构的指示采取行动的。关于中国为何给美国间谍寄来这些文件,从来没有人作出一种富有说服力的解释。
美国官员透露,从1992年至1996年,中国利用其新的核引信引爆了各种氢弹,包括一种在某些方面与W-88类似的氢弹。经过在罗布泊试验场进行的这一系列震撼大地的核爆炸,中国签署《全面禁止核试验条约》,发出了终止其核试验的信号。

调查:联邦侦探搜寻间谍

1995年9月28日,能源部开始了对可能盗窃W-88秘密的调查。在以后3年里,联邦官员不动声色地努力发现,他们中间是否有一名中国间谍。特鲁洛克先生和他的小组推论,如果发生了间谍活动,这种活动必定发生在W-88弹头进入设计研制阶段的1984年与这份中国文件所注明的日期1988年之间。
能源部官员把注意力集中于设计这种核弹的洛斯阿拉莫斯他们尤其仔细地审查在这些年里访问过中国或者会见过来访中国科学家的任何人。
弗鲁曼先生当时担任洛斯阿拉莫斯的反间谍主管,后来成了这种调查的公开批评者。他说,调查人员只审查那些由能源部出钱访华的人。
他说,至少有另外15名由中国人、中央情报局、空军或私人出钱访华的人没有受到审查。弗鲁曼先生说,这些访华者往往是高级武器设计者和高级官员——了解美国大多数武器机密并与中国同行有十分密切接触的人。
1996年5月,能源部向联邦调查局递交了一份包括21人的嫌疑犯名单。联邦调查局开始办理的刑事案件最终把目标缩小到李博士身上。李博士是一名在台湾出生、在洛斯阿拉莫斯工作的美国科学家。
李博士及其妻子西尔维亚曾于1968年和1988年访华。李太太是洛斯阿拉莫斯的一名秘书,经常会见来访的中国代表团。此外,李博士虽然接受的是机械工程师的训练,从来不是武器设计者,但因为他从事与计算机密码有关的工作,所以熟悉W-88以及其他许多核武器和机密(包括核引爆装置的发展)。
联邦调查局认为,它已有足够证据请求对李博士的电话进行秘密窃听,列举了他是主要嫌疑犯的20条理由。但司法部发现,这种证据并不令人信服,拒绝请求法院下令窃听。窃听电话是办理大多数间谍案件中的一个常规步骤。
弗鲁曼先生曾指责这种调查受到针对华裔美国人的种族偏见的站污,而联邦官员断然否认这种说法。但是,负责调查这起间谍案的参议院政府事务委员会的共和党人主席和民主党人首席委员都断定,联邦调查人员过早地把注意力集中在李博士身上。
在这起间谍案变得公开后,能源部长理查森(B. Richardson)建议,弗鲁曼先生应该受到处罚,因为甚至在对李博士产生怀疑之后,他仍允许李博士继续接触机密。
李博士今年被开除出洛斯阿拉莫斯,因为他违反保密规定,包括没有报告与外国人的接触。他没有受到犯罪指控,并否认进行过任何间谍活动。在他被开除后,调查人员发现,他把许多机密文件储存在一台不保密的计算机上,这增加了这些机密文件落入邪恶之手的风险。
要不是一系列与这次调查无关但与有关中国的情况的披露,这次调查很可能不会引起公众的关注。
1998年4月,《纽约时报》报道说,两家美国航天公司因向中国科学家提供火箭资料而受到刑事调查。
国会感到怒不可遏。众议院建立了一个由考克斯先生领导的特别委员会,调查政府日益开放的卫星出口政策是否危害国家安全。考克斯先生最近曾不成功地竞争众议院议长职位。
没有迹象表明,该委员会最终会研究核弹。该委员会由5名共和党人和4名民主党人组成,直到1998年10月才获悉中国人可疑的核间谍活动。这时离该委员会的受权期满只有几个月了。11月12日和12月16日,该委员会举行听证会,特鲁洛克先生被传唤作为主要证人出席了这两次听证会。1999年1月,经过3个月调查,该委员会完成了一份秘密文稿。5月,在就什么能公开与白宫进行长期争论之后,该委员会公布了一份长达827页的报告。有关核间谍活动的那一章仅37页,但成了大多数报刊的头版重要新闻。
该委员会用措辞激烈并附有生动的彩色照片和图表的文字指控说,中国间谍带走了与美国7种最先进的武器有关的重要秘密。
该委员会声称,中华人民共和国“窃取了与美国所有最先进的热核武器弹头有关的机密情报”,从50年代的笨拙设计跃进到更现代得多、也更致命得多的设计。
该委员会所引用的主要证据是中央情报局于1995年获得的那份中国文件,以及80年代对在利弗莫尔实验室发生的间谍活动进行的调查。这次调查得出的结论认为,中国十分可能获得了中子弹的设计秘密。该委员会报告的非保密版本没有提供1995年那份文件有关W-88的秘密细节的详情。
该委员会4名民主党人也签署了这份报告。但是,在报告公布后,这些民主党人之一、南卡罗来纳州众议员斯普拉特(J.M. Sptrat)就立即批评这份报告是匆忙炮制、草率肤浅和夸大事实的。他补充说,该委员会所传讯的证人“不具有能充分评估所丢失的情报的性质或价值的技术背景。”

辩论:分析家转向事实

自那时以来,斯普拉特先生的批评已得到许多第一流科学家和核弹设计者的共鸣,而且,后者的批评有过之而无不及。他们说,北京不必进行间谍活动,自力更生就能使其弹头小型化。
物理学家加温(R.L. Garwin)长期以来就核武器问题为华盛顿出谋划策,最近参加了由前国防部长拉姆斯菲尔德(D.H. Rumslfed)领导的一个两党小组。他说,“没有理由认为中国不能根据其自己开发的核技术”,为一系列现代导弹“制造完全合适的弹头”。
若干官员说,中国只是走了与其他核大国一样的道路,得益于对美国所取得的成就的大致了解。证明美国所取得的成就的证据是,氢弹能造得很小,但威力依然很大。
一名联邦官员在提及苏联、英国和法国在核引爆装置方面的突破时说:“每一个国家势必都会这么做。现在它们都已掌握了小型化技术。”
洛斯阿拉莫斯的国际安全研究室主任霍金斯先生因为间谍丑闻显然处于守势。他说,核弹和导弹的基本物理特性促使武器设计者向大致相同的方向努力。他说,为了获得最佳性能,工程师们必然会被引向大约16度宽的狭窄的鼻状锥体。
霍金斯先生说:“一旦你认识到这一点,这种认识就会促使每一个国家沿着相似的道路前进。最终所有武器系统看上去都将是相似的。相似必定与物理特性有关,而不是与间谍活动有关。”
这种观点目前没有被普遍接受。
首先在洛斯阿拉莫斯发出警报的分析家亨森博士说,在导弹鼻状锥体的设计中,没有什么能促使一个科学家把核引爆装置的中心部分设计成卵形。
他在提及这种高度保密的设计的形状时问道,难道科学和技术的分析能自动地“促使你想到西瓜的形状”?他说:“事实并非如此。”
亨森博士补充说:“毫无疑问,发生了严重的间谍活动。”
美国情报机构的态度就不这么坚决。分析家们得出的结论认为,间谍活动在北京的核进展中起了某种作用,但不能确定可与苏联在40年代窃取美国第一颗原子弹的设计相比的那种确凿联系。
一名仔细审阅过这种秘密资料的政府高级官员说:“人人都得出了同样的结论,但我们没有确凿证据。”
考克斯委员会所引用的去年完成的一项联邦情报研究成果说,在1984年至1988年之间丢失的美国机密使中国人能“超越其固有能力加速实现其核武器计划”——这个观点重复了洛斯阿拉莫斯最初的发现。
由美国情报界作出的一项于今年4月公布的损害评估说,间谍活动、公开可得的资料加上科学的敏锐,使中国人迈出的步伐变得更大了许多。这项评估说,窃取的秘密“可能帮助”北京研制了一种机动导弹,“或许加快了其发展未来核武器的计划的实现”。
6月,进行其自己的调查的总统对外情报顾问委员会说,国会和政府的领导人都在这起间谍案件中参与了“简单化和夸大化”。该委员会说,无论是引人注目的损害评估,还是信誓旦旦的明确保证,都没有得到充分证实。
而且,洛斯阿拉莫斯的官员霍金斯先生说,已知被中国人掌握的具体机密主要是在1995年的那份文件中详细列出的那些,对核弹制造者来说儿乎没有什么帮助,离特鲁洛克先生所谓的“路线图”更是相去甚远。至于设计者称之为物理包的氢弹内部构造,霍金斯先生说,文件“没有描述任何重要的东西”。
考克斯先生坚持认为,他的委员会所获得的高度机密的情报资料证明了比公开显示的更有说服力的案情。他说,“保密资料中有更多事实”把丢失的W-88的秘密与北京的核进展联系在一起。
但是,一名联邦官员所引用的有关中国核引爆装置的情报资料证明,中国的核引爆装置根本不是美国的核引爆装置的一模一样的翻版。
这名官员说:“事实上W-88的引爆装置略微更小一点。”他认为,北京可能是自力更生实现进步的。
仍然悬而未决的是,中国是如何首先获得W-88的秘密的,但正在形成的一种共识认为,对泄密的追查范围过快地缩小到了洛斯阿拉莫斯。
参议院以及总统对外情报委员会今年所进行的研究,都提出了有关联邦调查局和能源部是否过快地把注意力集中于武器实验室的严肃问题。没有证据准确地指出,武器实验室是泄密源头。
从1987年至1998年担任洛斯阿拉莫斯武器实验室反谍报主管的弗鲁曼先生指出,一份描述W-88弹头设计的机密文件发给了政府和军方各部门的548个邮件地址。一些政府专家认为,中国人在1995年那份文件中描述的资料来自工程计划,或者来自军事基地的秘密手册。
斯坦福大学的德雷尔博士曾参与总统对外情报顾问委员会的调查,他说:“这种情报随处可得发放的手册既有图片也有数字。如果一艘潜艇驶了进来,而且有问题,他们必须知道,他们是在与什么东西打交道。”
无论北京是如何实现其小型化进步的——是自力更生,是通过盗窃,还是这两者兼而有之——这种进步显然是自豪得足以公开夸耀的,至少在新墨西哥州山区的它的朋友们中间夸耀。亨森博士说,一个中国武器科学家几年前在洛斯阿拉莫斯夸耀这种突破,在一次公开的专家讨论会上说,中国在核武器方而已遥遥领先。
曾出席这次讨论会的亨森博士回忆说:“他说,在很长一段时间里他们只讨论圆形设计,只是后来才讨论西瓜形状的设计。”(张达文 译)
   
Spies vs. Sweat: The Debate Over China's Nuclear Advance
By WILLIAM J. BROAD

September 7, 1999, New York Times

When American bomb makers began visiting China in 1979, they were startled by increasingly pointed questions that suggested their Chinese peers were hot on the trail of the secret to building a modern nuclear arsenal. It allows hydrogen bombs to be made so small that many can fit atop a single missile or be fired from trucks, submarines and other mobile platforms.

China succeeded on Sept. 25, 1992, the news coming from a spy who told his American handlers that Beijing had exploded a bomb based on the miniaturization secret.

A team of scientists at the Los Alamos weapons laboratory in New Mexico set to work on a whodunit with huge implications: Was China's advance the result of espionage, hard work or some mix of the two?

Today, the debate rages on. Experts agree that spying occurred, but clash violently on how much was stolen and what impact it had on Beijing's advance, if any.

The Los Alamos team concluded in 1995 that China's stride was probably based on espionage. A report this year by a Congressional committee that made the case public went further, claiming that it would have been ''virtually impossible'' for China to have made small warheads ''without the nuclear secrets stolen from the United States.''

The Congressional report unleashed criticism from scientists inside and outside the Government who said the importance of the espionage was overstated, and that China could well have achieved the breakthrough on its own, as it insists publicly.

A review of the dispute, based on months of interviews and disclosures of weapons and intelligence secrets, suggests that the Congressional report went beyond the evidence in asserting that stolen secrets were the main reason for China's breakthrough.

The review also bolsters a point of emerging agreement among feuding experts: that the Federal investigation focused too soon on the Los Alamos National Laboratory and one worker there, Wen Ho Lee, who was fired for security violations. The lost secrets, it now appears, were available to hundreds and perhaps thousands of individuals scattered throughout the nation's arms complex.

Federal officials asked in recent days that some details about weapons design and intelligence sources not be published, and The New York Times agreed to withhold them.

For the Los Alamos team of detectives, the overall spy theory was supported strongly in 1995 when the Central Intelligence Agency obtained an internal Chinese document that included a description of the United States' most advanced miniature warhead, the W-88. Revealing for the first time their top evidence in the case, the document's secret contents, Federal officials say the Chinese text cited five key attributes of the warhead, including two measurements accurate to within four-hundredths of an inch.

But the critics, who are also revealing new information, insist that Beijing, even if it spied, made the miniaturization breakthrough on its own, pursuing it for at least 13 years, from 1979 to 1992.

The prowess of Chinese scientists, American experts said, is suggested by a camera they built for photographing nuclear blasts, which was far better than a similar one made by the United States.

''They don't need any help from us,'' said Harold Agnew, a past Los Alamos director, visitor to China and Federal intelligence adviser. ''They're just curious, as we are curious about them.''

Deconstructing the damage wrought by espionage is an imprecise art that mixes inference, evidence and deduction. In the vacuum between what is known and what is suspected, personal, partisan or institutional bias often rushes in.

The debate over Chinese spying has been blurred by issues that include Republican distaste for President Clinton's China policy, accusations of racial bias in the investigation and fears among scientists that the uproar is prompting security measures so tight as to damage work, morale and recruitment.

As in most spy cases, the evidence is open to interpretation. Several critics familiar with the Chinese document obtained by the C.I.A. said that its description of the American warhead was not by itself sufficient to build a miniaturized warhead.

The Energy Department official who supervised the Los Alamos inquiry, Notra Trulock, agreed with this assessment but said the information was secret and had never been mentioned in any public document or Internet posting. Anyone who had it, he and his team reasoned, must have also obtained access to a much broader range of secrets about the warhead's design.

In addition, Mr. Trulock said in an interview, knowing the approximate size and shape of the components provided a road map to Chinese bomb makers, probably allowing them to skip years of preliminary testing.

Mr. Trulock added, however, that the Congressional committee was too categorical in its report, which was based in part on his testimony.

''When I testified, I used the appropriate caveats to express uncertainties in our evidence and our conclusions,'' said Mr. Trulock, formerly the Energy Department's intelligence chief. ''We typically said: 'Probably this. Probably that.' '' The committee, he said, ''made judgments'' about the centrality of spying in China's breakthrough.

 Representative Christopher Cox, a California Republican who was chairman of the committee, defended the work of his staff of 47, which included no one with nuclear design experience. The panel, he said in a lengthy interview, drew largely on Clinton Administration witnesses for its expertise. The conclusion that espionage allowed Beijing to skip decades of research, he said, was an appropriate one, based on the Government's own evidence.

''Judgment matters,'' he said, responding to Mr. Trulock's criticism. ''We don't know everything to a certainty. The question is what is more likely than not.''

In the interview, Mr. Cox expressed surprise when told of the depth and breadth of China's interest in the miniaturization secret. He also played down the idea, cited by Federal skeptics of Chinese spying, that most of the world's nuclear powers have figured out the secret of miniaturization.

Can China, Mr. Cox asked, ''develop it indigenously because France did? That is a stretch. It's almost apples and oranges.''

The Secret
America Shrinks An Atomic Match


From the dawn of the nuclear age, miniaturization has been an obsession of weapons designers. The world's first atomic bomb, designed by the Los Alamos laboratory and detonated in the New Mexico desert in July 1945, was an awesome but cumbersome affair. A lump of plutonium the size of a softball was surrounded by a much larger ball of high explosives that was five feet wide and made up of 32 explosive charges and 64 detonators. Big as a car, it could not have fit into a small airplane, let alone a missile.

In 1952, American physicists made an important breakthrough: the H-bomb. Roughly a thousand times more powerful than the first atomic weapon, the hydrogen bomb was a two-stage device. Inside its dense casing, an atomic explosion -- called the primary -- worked as a match to kindle an even more powerful detonation by the bomb's hydrogen fuel, which was known as the secondary.

Size was an issue from the start. The first hydrogen bomb stood two stories high and weighed 82 tons. It would be militarily useful only if it could be shrunk, and over the next few years, the country's best physicists set out to do just that. After considerable trial and error, they figured out that they could obtain the same kind of explosive power from a smaller package. A main breakthrough centered on the large, heavy atomic match. By shaping its plutonium fuel into an ovoid, roughly like a watermelon, scientists were able to drastically shrink the size and number of the explosives that triggered the nuclear blast.

After at least one flop, the radical idea roared to life in July 1957 in a nuclear explosion in the Nevada desert, according to Chuck Hansen, author of a detailed history of America's early nuclear efforts. It had taken the United States a little more than five years to move from the first hydrogen bomb to its miniaturized cousin.

The development had profound implications for the cold war's nuclear competition.

Shrinking the atomic trigger from something roughly the size of a washing machine to something smaller than a football allowed weapons designers to put thermonuclear arms atop small missiles that could be launched from submarines or mobile platforms like trucks. Arms would no longer be confined to bombers or silos in the ground.

The advance meant weapons could now be carried, quite stealthily, closer to enemy shores and could be made safer from attack. It also meant warheads could fit into the cramped spaces of narrow nose cones, which streaked faster to Earth than blunter shapes and were less buffeted by winds during the fiery plunge, making them more accurate.

The first warhead in the new generation of weapons, the W-47, was less than half the size of the bomb that leveled Hiroshima but up to 80 times more powerful. In 1960, when the first Polaris submarine put to sea, each of its 16 missiles was armed with a W-47.

The weapons continued to evolve, and by all accounts, the apex was reached in the 1980's with the W-88, one of the most deadly weapons in the American arsenal.

The warhead, made for submarines, first went to sea a decade ago and is considered quite powerful for its small size. The precise size is secret. But at least eight W-88's can fit atop the Trident D-5 missile, which is less than seven feet wide. Since Trident subs have 24 missiles, a single submarine can carry up to 192 of the thermonuclear arms.

Today, American submarines on patrol in the Atlantic carry the small warheads. And the Navy is adding them to its Pacific fleet, so in the next few years the W-88 is likely to be aimed at China.

The Chinese
Late to Start, Quick to Excel


China was late in joining the nuclear club, but showed considerable skill when it did.

Beijing detonated its first bomb in 1964. The tricky design was based on uranium, like the Hiroshima bomb, but saved costly fuel and made the bomb lighter, increasing its military value.

Sidney D. Drell, a Stanford physicist and Clinton Administration adviser, writing in ''China Builds the Bomb'' (Stanford University Press, 1988), called the feat ''enormously impressive.'' Beijing's first hydrogen bomb came just 32 months later.

 By comparison, the step from nuclear to thermonuclear took London 66 months, Moscow 75 months, Washington 87 months and Paris 103 months, said Robert S. Norris of the Natural Resources Defense Council, a private group in Washington that monitors nuclear arms.

China set off just 6 test blasts to get to the H-bomb stage, versus 31 for the United States. The low number was typical. While developing at least six types of weapons, Beijing over the decades conducted relatively few nuclear tests, 45 in all, versus 1,030 for the United States.

The evidence strongly suggests that China, in its first phases of missile building, had no idea how to shrink thermonuclear arms. According to ''China's Strategic Seapower'' (Stanford University Press, 1994), the warhead for the submarine missile deployed by Beijing in the 1970's weighed 1,300 pounds, more than twice the old American W-47, suggesting that the Chinese were still using a spherical atomic match to ignite hydrogen bombs.

China's land force was modest. Starting in the 1980's, it deployed about 20 missiles that can now reach anywhere in North America, each topped by a single warhead that can unleash a force equivalent to up to five million tons of high explosives. That is about 300 times stronger than the Hiroshima bomb.

The big warheads are not particularly accurate, but they fit China's professed war doctrine -- to fire nuclear arms only in retaliation. The big missiles can, if necessary, hit a city.

China's interest in building smaller weapons was spurred, in part, by the United States' development in the late 1970's of a high-accuracy design known as the Missile Experimental, or MX, that bristled with 10 warheads. Though meant primarily to unnerve Moscow, the weapon also worried Beijing, which quickly grasped that its handful of big land-based missiles looked like sitting ducks that could be destroyed in a first strike of precisely aimed hydrogen bombs.

Beijing's unease grew as the American Navy in the late 1970's unveiled plans for a new submarine-launched missile nearly as unerring as the MX and bearing an even more powerful warhead -- the W-88.

American intelligence agencies knew little about China's nuclear program and modernization plans, if any, before President Richard Nixon's visit to China in 1972. But the military ties that followed the Nixon diplomatic initiative opened the door.

By 1979, American nuclear arms designers and security experts were starting to visit their Chinese peers, weapons labs and Lop Nur, the sprawling site in China's western desert where prototype nuclear weapons were detonated.

From Los Alamos alone, at least 85 scientists and officials made trips from 1979 to 1990, according to Robert S. Vrooman, a former C.I.A. officer who at the time directed counterintelligence at Los Alamos.

Top visitors included Dr. Agnew, the past director of the weapons lab; Danny B. Stillman, its head of intelligence; and George A. Keyworth 2d, a physicist who later became President Reagan's science adviser.

The benefits were judged to far outweigh the risks that arms scientists in informal settings and conversations might, by accident or design, give away secrets. And indeed, the Americans learned much.

''This was a huge intelligence game for the United States,'' said a United States official who spoke on the condition of anonymity. ''At the beginning we knew zip about China.''

One discovery was that parts of the Chinese program were quite advanced, including technologies for bomb development.

''They have excellent facilities, some better than ours,'' said Dr. Agnew, who in 1979 and 1982 was among the first visitors.

For instance, he said, the Chinese were able to peer into fiery blasts with an advanced camera known as pinex, revealing details to aid warhead development.

The American version of the device had one axis, he said, the Chinese version two, doubling its usefulness. ''It's much better,'' Dr. Agnew said.

The American visitors also learned much about what China lacked. From a barrage of inquiries over the years, it became clear that Beijing was eager to learn everything it could about shrinking the atomic trigger. The questions were regular, increasingly pointed and never answered, American officials said, insisting that Beijing got no secrets that way.

But in one case, investigators became suspicious about an American scientist at the Livermore weapons lab in California who in 1979 had talked with Chinese scientists.

The suspect, born in Taiwan, never confessed. But some Federal investigators, in an investigation code-named Tiger Trap, feared the scientist had compromised not only the design of the W-70, a neutron bomb, but the secret to making small atomic triggers.

Weapons experts say that the crucial insight of the watermelon shape can be communicated with a few comments, a hand motion or a simple drawing on the back of an envelope, although years of computing, calculation, experiment and factory labor are then needed to turn the idea into nuclear blasts.

 ''The real challenge is not in the design, it's in the manufacturing,'' said Houston T. Hawkins, head of international security studies at Los Alamos. For example, he said, plutonium, one of the most complex metals known to science, is difficult to cast because of its odd ways of reacting with other metals and materials. ''It's a strange beast,'' he said of the dense metal that fuels most atom bombs.

The Breakthrough
China Takes Giant Nuclear Step


China finally succeeded in exploding a miniaturized bomb on Sept. 25, 1992, American officials revealed. It took intelligence analysts more than two years to fully understand what China had accomplished, its feat becoming clear only after a Chinese nuclear expert who had been recruited to spy for the United States delivered an intriguing report to his American handlers.

The spy said that China's September test blast, initially viewed by American analysts as routine, was anything but. The bomb detonated that day was miniaturized with a core, the spy said, in the distinctive shape of an ovoid, indicating China had begun to master the art of making modern warheads.

In the mid-1990's, the task of tracking the technical ins and outs of other nations' nuclear programs fell to the national weapons labs. Among the sleuths was Dr. Robert M. Henson, an experienced weapons designer at Los Alamos who had been analyzing intelligence on foreign programs since 1988.

In January 1995, Dr. Henson said in an interview, he began looking more closely at how China had solved the miniaturization puzzle. For help he turned to Lawrence A. Booth, a friend who specialized in Russian analyses.

''We kept looking into it for two weeks,'' Dr. Henson recalled. ''Then, we decided to do something.''

They drew up their analysis and eventually took it to Mr. Trulock, who the previous year had become director of intelligence at the Energy Department, which oversees Los Alamos. Mr. Trulock, who has a bachelor's degree in political science and no formal technical training, said he wanted to bring in other nuclear experts, particularly ones who had long experience in developing the miniaturized nuclear triggers for hydrogen bombs. John L. Richter of Los Alamos, a scientist who filled that void, joined the team.

The group looked more closely at a clue provided by the Chinese spy, who described the size of the bomb's atomic core with an analogy to a common household object, officials said in a new disclosure. Working from that, the scientists calculated a more precise size and Dr. Henson and Dr. Richter went through the American stockpile of nuclear arms, looking up measurements to see if any matched.

The atomic trigger of the W-88, they discovered, was close enough in size to raise suspicions.

The Energy Department held meetings in which the Los Alamos team was joined by analysts from the C.I.A. and the Defense Intelligence Agency. Federal officials now say the intelligence agencies were skeptical, reasoning that too much was being made of a foreigner's rough analogy. But the Energy Department and the Los Alamos team felt the evidence was provocative.

The breakthrough came in 1995, as has been previously disclosed, when a Chinese Government official sent a package of secret Chinese documents to American officials.

Mr. Trulock said the most revealing document, dated 1988, laid out China's nuclear modernization plans for Beijing's First Ministry of Machine Building, which, among other things, made missiles and nose cones. It not only described China's plans but compared them to the nuclear arms of the American arsenal.

Relatively crude hand drawings sketched out the nose cones enveloping the W-88, the W-87, the W-78, the W-76, the W-62 and the W-56 -- warheads of the Trident, MX and Minuteman missiles -- and also gave their overall weights and dimensions.

In itself, these were not damning. Though still officially classified secret in some cases, such information by then was widely available in many unclassified American papers and articles.

But the Chinese document, some 20 pages in translation, went on to give sensitive data about the W-88, Federal officials revealed. It accurately described the shape of the atomic trigger as not spherical and said it was situated in the nose cone's narrow forward end -- an arrangement used in some but not all American warheads. And it correctly described the hydrogen fuel, or secondary, as having a spherical shape.

More unsettling to the team, it described the width of the casing that surrounds the atomic trigger to within a millimeter, or four-hundredths of an inch. ''That's pretty damn accurate,'' Mr. Trulock recalled.

A senior Federal official agreed. ''That opened eyes,'' he said. ''It seemed to confirm earlier assessments that had seemed insubstantial.''

Mr. Trulock said his team later found that the Chinese document gave a similarly exact measure for the width of the W-88's secondary, or hydrogen stage. ''Primaries are the long pole in the tent,'' he said, referring to the importance of the atomic trigger. ''But that measurement was as good as the one for the primary.''

 The C.I.A. eventually concluded that the agent who sent the documents was acting under the instruction of Chinese intelligence. No one has ever come up with a persuasive explanation of why China sent the documents to American spies.

From 1992 to 1996, American officials revealed, China used its new atomic match to ignite a variety of hydrogen bombs, including one similar in some respects to the W-88. After this series of blasts shook the ground at the Lop Nur test site, China signed the Comprehensive Test Ban Treaty, signaling an end to its nuclear experimentation.

The Investigation
Federal Sleuths Hunt for a Spy

The Energy Department opened an investigation into the possible theft of W-88 secrets on Sept. 28, 1995, and over the next three years, Federal officials quietly tried to find out whether there was a Chinese spy in their midst.

If espionage occurred, Mr. Trulock and his team reasoned, it must have happened between 1984, when the warhead entered engineering development, and 1988, the date of the Chinese document.

Energy Department officials focused on Los Alamos, which had designed the bomb. They looked particularly closely at anyone who had traveled to China in those years or met visiting Chinese scientists.

Mr. Vrooman, then head of counterintelligence at Los Alamos and later a vocal critic of the inquiry, said investigators scrutinized only those people whose trips to China were paid for by the Energy Department.

Left unexamined, he said, were at least 15 additional people whose trips were paid for by the Chinese, the C.I.A., the Air Force or privately. These travelers tended to be top weapons designers and high officials -- the people who knew the most American arms secrets and had the most intimate contact with Chinese peers, Mr. Vrooman said.

In May 1996, the Energy Department turned over a list of a dozen suspects to the Federal Bureau of Investigation, which began a criminal case that eventually narrowed to Dr. Lee, an American scientist of Taiwanese birth working at Los Alamos.

Dr. Lee and his wife, Sylvia, had traveled to China in 1986 and 1988. Mrs. Lee was a secretary at Los Alamos who often met visiting Chinese delegations. And Dr. Lee, though a mechanical engineer by training and never a weapons designer, was familiar with the W-88 and many other nuclear arms and secrets (including the atomic trigger advance) because of his work on secret computer codes.

The F.B.I. believed it had enough evidence to seek a secret wiretap on Dr. Lee's phone calls, citing 20 reasons he was a prime suspect. But the Justice Department found the evidence unpersuasive and refused to seek a court order for the eavesdropping, a routine step in most spy cases.

Mr. Vrooman has charged that the inquiry was marred by a racist bias to target Chinese-Americans, an assertion Federal officials have vehemently denied. But the Republican chairman and the ranking Democrat of the Senate Governmental Affairs Committee, which investigated the spy case and heard testimony from Mr. Vrooman, concluded that Federal investigators had focused prematurely on Dr. Lee.

After the spy case became in public, Bill Richardson, the Secretary of Energy, recommended that Mr. Vrooman be disciplined for letting Dr. Lee have continuing access to secrets even after doubts about him had been raised.

Dr. Lee, fired this year from Los Alamos for security violations, including failing to report foreign contacts, has been charged with no crime and has denied any spying. After his ouster, investigators found that he had loaded many secret files onto an unsecured computer, raising the risk that they could have fallen into the wrong hands.

The inquiry most likely would not have come into public view had it not been for a series of unrelated disclosures about China.

In April 1998, The Times reported that two United States aerospace companies were under criminal investigation for providing rocket data to Chinese scientists.

A furor erupted in Congress. The House created a select committee, led by Mr. Cox, who had recently vied unsuccessfully for the House speakership, to look into whether the Administration's increasingly open policies on satellite exports had compromised national security.

There was no hint the committee would end up studying nuclear bombs. Composed of five Republicans and four Democrats, the committee did not learn of the suspected Chinese nuclear espionage until October 1998, just a few months before its mandate expired. On Nov. 12 and Dec. 16 it held secret hearings in which Mr. Trulock was called as the star witness.

In January, after three months of investigation, the committee completed a secret manuscript. In May, after a long argument with the White House over what could be made public, it released an 872-page report. The chapter on atomic espionage, just 37 pages, garnered most of the headlines.

In fiery prose accompanied by vivid color pictures and charts, the committee charged that Chinese spies had carried off vital secrets about seven of America's most advanced arms.

 The People's Republic of China, it alleged, ''has stolen classified information on all of the United States' most advanced thermonuclear warheads,'' leaping from the clumsy designs of the 1950's to those that are far more modern and deadly.

The main evidence cited was the Chinese document obtained by the C.I.A. in 1995 and an inquiry in the 1980's into spying at the Livermore lab that concluded China had most likely obtained design secrets of the neutron bomb. The unclassified version of the committee's report gave no details of the 1995 document's secret details about the W-88.

The report was signed by the committee's four Democrats. But immediately after its release, Representative John M. Spratt Jr. of South Carolina, one of the Democrats, criticized it as rushed, superficial and exaggerated. The witnesses heard by the committee, he added, ''did not have the technical background to fully assess the nature or value of the information lost.''

The Debate
Analysts Sift For the Truth

Since then, Mr. Spratt's critique has been echoed and amplified by a range of top scientists and bomb designers who say Beijing could have miniaturized its warheads on its own without spying.

Richard L. Garwin, a physicist who has long advised Washington on nuclear arms, recently on a bipartisan team led by former Defense Secretary Donald H. Rumsfeld, said, ''there is no reason to believe that China could not have built perfectly adequate warheads'' for a range of modern missiles ''from nuclear technology that it developed itself.''

China, several officials said, simply went down the same path as other nuclear powers, helped along by the general knowledge of what the United States had achieved: proof that hydrogen bombs can be made very small but nonetheless very powerful.

''Every state has come to it,'' said one Federal official, referring to breakthroughs in atomic triggers by the Soviet Union, Britain and France. ''Now they've got it too.''

Mr. Hawkins, the head of international security studies at Los Alamos, which is clearly on the defensive because of the spy scandal, said the basic physics of bombs and missiles push weapons designers in roughly the same direction. To obtain the best performance, he said, engineers are invariably led toward narrow nose cones about 16 degrees wide -- if cut from a pie, a very modest slice.

''Once you realize that,'' Mr. Hawkins said, ''it drives every nation down similar paths. Eventually, all weapons systems will look alike. It has to do more with physics than espionage.''

That view is not universally accepted.

Dr. Henson, the analyst who first sounded the alarm at Los Alamos, said there was nothing in the design of missile nose cones that propelled a scientist to shape the core of an atomic trigger into an oval.

Do scientific and technical analyses automatically ''draw you to a watermelon?'' he asked, alluding to the shape of the top-secret design. ''That's not true.''

''It's beyond a shadow of a doubt,'' Dr. Henson added. ''Major espionage took place.''

American intelligence agencies are less categorical. Analysts have concluded that espionage played a role in Beijing's advance, but cannot identify a hard link comparable to the Soviet Union's theft in the 1940's of the American design for the first atom bomb.

''Everybody has come to the same conclusion,'' said a top Administration official who has closely scrutinized the secret data. ''We don't have a smoking gun.''

A Federal intelligence study done last year, which the Cox committee drew on, said American secrets lost between 1984 and 1988 let the Chinese ''accelerate their nuclear weapons program well beyond indigenous capabilities,'' a view that echoed the original Los Alamos finding.

A damage assessment by the American intelligence community, made public in April, said a mix of espionage, openly available data and scientific acumen had greatly lengthened Chinese strides. Stolen secrets, it said, ''could help'' Beijing develop a mobile missile and ''probably accelerated its program to develop future nuclear weapons.''

In June, the President's Foreign Intelligence Advisory Board, which did its own investigation, said both Congressional and Administration leaders had engaged in ''simplification and hyperbole'' in the spy case. Neither dramatic damage assessments nor categorical reassurances, it said, were wholly substantiated.

And Mr. Hawkins, the Los Alamos official, said the specific secrets known to have been seized by the Chinese, principally those detailed in the 1995 document, would have been little help to a bomb maker, and far from Mr. Trulock's road map. As for an H-bomb's innards, what designers call the physics package, Mr. Hawkins said the documents ''describe nothing significant.''

Mr. Cox insisted that highly classified intelligence data available to his committee showed a more persuasive case than has emerged publicly. ''There are more interpolating facts'' that closely tie lost W-88 secrets to Beijing's advance, he said.

But a Federal official cited intelligence data about China's atomic trigger showing it to be anything but an exact copy.

''It turns out the W-88's is slightly smaller,'' said the official, who believes Beijing may have made the advance on its own.

It remains unresolved how China got the W-88 secrets in the first place, but a consensus is emerging that the search for the leak narrowed too quickly to Los Alamos.

Studies by the Senate as well as the President's foreign intelligence board this year raised serious questions about whether the F.B.I. and Energy Department had too quickly focused on the weapons lab. No evidence has pinpointed it as the leak's source.

Mr. Vrooman, the head of counterintelligence at the laboratory from 1987 until 1998, noted that one secret document describing the design of the W-88 warhead went to 548 mailing addresses throughout the Government and military. Some Administration experts believe the data described by the Chinese in the 1995 document came from engineering plans or from secret manuals on military bases.

''That kind of information was widely available,'' said Dr. Drell of Stanford, who served on the President's advisory board investigation. ''The manuals that went out had pictures and numbers. If a submarine came in, and there was a problem, they had to know what they were dealing with.''

However Beijing made its miniaturization advance -- on its own, by theft or a combination of the two -- it is apparently proud enough to boast about it publicly, at least among its friends in the mountains of New Mexico. Dr. Henson said a Chinese arms scientist, Sun Cheng Wei, bragged of the breakthrough at Los Alamos a few years ago, telling an open seminar that China had forged significantly ahead in nuclear arms.

''What he said,'' recalled Dr. Henson, who attended the talk, ''was that for a long time they were dealing only with round designs, and then only watermelons.''


Some secret specifications of the W-88, an American miniature hydrogen bomb, that were found in a Chinese document.
间谍vs汗水:有关中国核进展的辩论 - kktt - 长缨在手  敢缚苍龙
 
''Less but More'' Early bombs were behemoths compared with modern miniature devices. The W-88, the U.S. arsenal's most modern warhead, though tiny, is dozens of times more powerful than the bomb that leveled Hiroshima.
间谍vs汗水:有关中国核进展的辩论 - kktt - 长缨在手  敢缚苍龙
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