case the missiles home against their talgets by the use of infrared radiation orradar, some nissil-es carrying their own active radar and some on]-y d.etecto"s of the rad.a.r reffections from the target caused by an illjminating beam on the ground or in rhe attaching aircraft. f2l" trIhether these new systems could" countea aircraft delivering nuclear weapons L'ou-ld depend on the rel-ative numbers of weapons and on the acceptable numbe"s ofpenetrators" Thus, it wou].d be quite dj.fficult to have an air defence system capable of cormtering the planned. 3,000-A-T,CM United States nuclear force if it were directed. against i.ndustrial- targets in the Soviet Union. 0n the other ha1d,it would be a much easier task to counter manned bombers flying over and attackingfield.s of fCBM si1os. 122" SlBl{-launching subnarines could be imperilted either by an attack while they are in po"t, by area search on the open ocean, or by being tlailed. Submarines are highly vu-lnerable in port. As an example " one might consider the not uncoomon occurrence of three submarines s imu-l,t aneous 1y in a particular port, vith each submarine housing 16 nissiles, each with 10 MIRVS. lthese \80 MIRVS could be destroyed by one single megaton r^res.pon, an exchange ratio of lrSO warheads for 1.A/35 /39? English Arlnex Page \9 But submarines on the open ocean remain quite invu_Lnerable, despite very largeannuaf expenditr.ues for research arid deviopnent cn antisubmarine warfaretechniques. This is mainly due to the difficulties inherent in their detectionand l-ocalization "
**Analysis**
This text appears to be discussing the military capabilities of the United States and the Soviet Union, specifically the use of missiles and submarines in nuclear warfare. The language and concepts used, such as "nuclear force", "missiles", "radar", and "antisubmarine warfare", suggest that the text is related to military strategy and technology.

**Category**
Science and technology, Defense