过去几年中,导弹防御技术进展很快,而进攻方面缺乏相应的进展,因而,美国洲际弹道导弹领先于潜在敌人防御系统报复能力的优势已逐渐地削弱。 这就是权威的观察家们一致的悲观的看法,然而不久以前,观察家们还自负地反映了国防部的看法,他们认为美国导弹力量领先于任何一个潜在敌人导弹防御方面若干年（A.W.Jan　20.1964.P.72）。依靠导弹力量对付人侵者报复性袭击的威胁已是近来美国核防御方面的基石。 Over the past few years, while missile defense technology has progressed rapidly and its offensive lack of progress, the advantages of the U.S. intercontinental ballistic missile ahead of the retaliatory potential of a potential enemy defense system have gradually been weakened. This is the unanimous pessimistic view of the authoritative observers, but not too long ago, the observers conceited their own view of the Department of Defense’s view that the U.S. missile force is ahead of any potential enemy missile defense for several years (AW Jan 20, 1964, P .72). The threat of relying on missile forces to deal with retaliation by invaders has been the cornerstone of the recent nuclear defense in the United States.