Anti-ballistic missile

An anti-ballistic missile (ABM) is a missile designed to disable the warheads of intercontinental ballistic missiles: a missile designed to counter the strategic ballistic missiles used to deliver nuclear weapons or their elements in flight trajectory. ABMs may also be used against Chemical or Biological payloads.

ABMs have had a rather chequered history. Soviet experiments in the 1960s with an ABM system based near Moscow failed. American experiments achieved some success in intercepting missiles launched from the Western Test Range toward a test site on Kwajelein[?] atoll. However, the great cost and dubious feasibility of building successful missile detection and interception systems with 1970s technology, led to the ABM treaty of 1972, which restricted the deployment of missiles designed to shoot down each other's ICBMs. Under the ABM treaty, each country was allowed to deploy a single ABM system to protect a single target. The Soviets deployed a system designed to protect Moscow. The US deployed a system called Safeguard to defend ballistic missile sites in the Northern Plains in 1975. Few people seriously think either system would have been very effective. (In December 2001, the US announced its intention to withdraw from the treaty.)

The Reagan-era Strategic Defense Initiative, along with research into various energy-beam weaponry, brought new interest in the area of ABM technologies. Extensive research and some experiments proved that several concepts for space-based systems (X Ray Lasers, "smart pebbles", etc) were not feasible with then current technology. Nothing was deployed operationally until Patriot antiaircraft missiles were used in the 1991 Gulf War to attempt to intercept Iraqi Scud missiles. Post-war anlayses show that the Patriot was largely ineffective because of the limited range of its radar and the control system's inability to discriminate payloads from other objects when the Scud missiles broke up (or were broken up -- it's not clear which) during reentry. On the other hand, the Scud itself was highly inaccurate and not very reliable. It was more a psychological than real threat to military targets. The Patriot might have been more effective against a missile that was a more realistic threat.

Testing of ABMs and ABM technology continued through the 1990s with mixed success. While there is little doubt that 1970s style ABM missiles with nuclear warheads could achieve reasonable intercept rates, use of non-nuclear interceptors requires that the interceptor physically contact the incoming payload -- a much more difficult problem. There are also many unresolved issues with warhead discrimination and decoy deployment. There is little doubt that occasional intercepts are possible. The issue is whether an ABM system is a cost effective deterrent or whether a potential enemy will simply deploy a few more missiles with more warheads.

The election of George W. Bush in 2000 has led to the renewed interest and several ABM tests, as the U.S. military and their new political masters seek to demonstrate the feasibility of shooting down ballistic missiles. In contrast to the Reagan era Strategic Defense Initiative which was intended to shield the United States from a massive attack by the Soviet Union, the purpose of the Bush era ABM's (National Missile Defense) are the much more limited goal of shielding the United States from a limited attack by a rogue state. It remains to be seen whether a system reliable enough to be useful operationally can be developed. Bush and his advisors appear to be determined to deploy a system whether it will work or not and have proposed to develop a dual purpose test and interception facility in Alaska. The Alaska site, it should be mentioned, might be effective against missiles launched from East Asia, but is not likely to provide much protection from missiles launched from Southwest Asia. Bush has used the September 11, 2001 Terrorist Attack to justify the need for such a shield. This is despite the fact that a missile shield would not have protected the nation from that attack, which was not launched via missiles (and would not protect the U.S. from any future attacks which might choose to simply bypass the missile shield).

In 1998 the Israeli military conducted a successful test of their Arrow ABM, developed in Israel with American assistance. Designed to intercept incoming missiles traveling at up to two miles per second, the Arrow is expected to perform much better than the Patriot did in the Gulf War.

See: ABM treaty, nuclear disarmament, nuclear proliferation, nuclear warfare, nuclear weapon