The Continuing Impact of the Nuclear Revolution

Article excerpt

The demands on the performance of defenses against an attack by even a single missile carrying a nuclear warhead must be extremely high for the defense to be considered effective.

The advent of nuclear weapons with their tremendous increase in destructive force decisively shifted the balance between offensive and defensive forces. This change has profound implications in judging the wisdom of any plans to deploy defenses against ballistic missiles carrying nuclear warheads.

The history of warfare is replete with competition between offense and defense, from the sword and the shield to the struggle between assault troops and fortifications. World War II provides lessons on the relative effectiveness of offense and defense. The French attempted to erect an impenetrable defense in the form of the Maginot Line against Germany, only to have Adolf Hitler's mobile armored forces circumvent the defenses by taking a more northerly route. An innovative offense defeated a static defense. In the Battle of Britain, Hitler's Luftwaffe carried out repeated massive attacks against Britain. However, each mission suffered losses on the order of 10 percent, inflicted by the Royal Air Force, which was assisted by radar, a newly introduced technology, and cryptography, which together yielded warning of such attacks. As a consequence, the attacking forces were reduced by a third for each 10 sorties flown, a level of attrition that proved unacceptable. History contains many such examples of both successes and failures of defenses against conventional attacks.

Nuclear weapons, however, profoundly changed the relationship between offense and defense because they increased the explosive power of a payload of a given weight and size by a factor of one milliona very profound change indeed. The demands on the performance and reliability of defenses against an attack by even a single missile carrying a nuclear weapon must therefore be extremely high for the defense to be considered effective. When the Germans attacked Britain during World War II with primitive ballistic missiles, none were intercepted, but the damage was limited because the missiles carried conventional explosives. Had they carried nuclear warheads, a single missile would have devastated London. Defense against ballistic missiles is therefore a totally different problem depending on whether such missiles carry conventional or nuclear payloads.

Against this background, national missile defense has re-entered the national and international political agenda. The AntiBallistic Missile (ABM) Treaty, signed in 1972, explicitly forbids deployments of defenses that protect the entire territory of signatory nations against strategic ballistic missiles. The basis of this treaty was the mutual recognition during the Cold War that the United States and the Soviet Union had attained a strategic balance based on deterrence: neither side could launch a nuclear attack against the other without incurring the risk of a retaliatory strike that would produce unacceptable damage. To appreciate the extent of the potential destruction, it should be remembered that the combined yield of the two nuclear weapons that killed 250,000 people in Hiroshima and Nagasaki would equal only about one-tenth the yield of a single nuclear weapon in today's arsenal.

At the height of the Cold War, the United States and Soviet Union deployed more than 60,000 nuclear weapons in aggregate. Today the number of nuclear weapons in the world has shrunk by about one-half, with the overwhelming majority in the hands of Russia and the United States. At the same time, the so-called rogue states still have no nuclear weapons, although North Korea may have enough plutonium for one or two.

Nuclear weapons can be delivered to the U.S. homeland in many ways, of which the intercontinental ballistic missile is only one and the one requiring the most technological prowess. Nuclear weapons can be dropped from airplanes of almost any size, delivered by cruise missiles traveling in the earth's atmosphere, detonated on ships in U. …