..Russia, which built a missile defense system around Moscow in the 1960s that survives to this day, relied from the start on nuclear-armed interceptors. Although U.S. defense experts regard the Russian system as anachronistic, Russian military officials worry that the United States will eventually adopt the nuclear approach, according to Pavel Podvig, editor of an authoritative book about Russian strategic nuclear forces published last year by the Center for Arms Control Studies in Moscow.
"They believe strongly that you cannot get an effective missile defense system using hit-to-kill," Podvig said.
The first real and successful ABM hit-to-kill test was conducted by the Soviet PVO forces on the 1st of March 1961. An experimental V-1000 missile (part of the "A" ABM programme) launched from the Sary-Shagan test range, destroyed at an altitude of 25 km a dummy warhead released by a R-12 ballistic missile launched from the Kapustin Yar cosmodrome. The dummy warhead was destroyed by the impact of 18 thousand tungsten-carbide spherical impactors 140 seconds after launch. The first US similar test was conducted on the 19th of July 1962 and involved an Nike Zeus ABM simulating a nuclear hit by passing close to the target dummy, i.e. not a direct hit. The V-1000 missile system was nonetheless considered not reliable enough and abandoned in favour of nuclear-tipped ABMs.
The only other ICBM ABM system to reach production was the Soviet A-35 system. It was initially a single-layer exoatmospheric (outside the atmosphere) design, using the Galosh (SH-01/ABM-1) interceptor. It was deployed at four sites around Moscow in the early 1970s.
Originally intended to be a larger deployment, the system was downsized to the two sites allowed under the 1972 ABM treaty. It was upgraded in the 1980s to a two-layer system, the A-135. The Gorgon (SH-11/ABM-4) long-range missile was designed to handle intercepts outside the atmosphere, and the Gazelle (SH-08/ABM-3) short-range missile endoatmospheric intercepts that eluded Gorgon. The system as it existed during the 1970s is thought to have been similar in capability to that of the former U.S. Safeguard system.
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China is not opposed to every form of missile defense. China considers lower-tier theater missile defenses to be "legitimate" missile defenses since these systems can only protect small areas from missile attacks. China's approval of lower-tier missile defenses also stems from the fact that China has purchased S-300 (NATO designation: SA-10) anti-aircraft missile systems from Russia which have an inherent anti-missile capability. According to an unconfirmed source,
China is also developing its own TMD, called KDI. KDI is said to have a range of 25 km with a maximum speed of Mach 4 and is capable of hitting a number of missiles. http://cns.miis.edu/research/china/chinamd.htm#China's%20Indigenous%20Missile%20Defense
ASAT Test Demonstrated
Missile Defense Capability
China used a kinetic kill vehicle instead of the ‘shot-gun blast’ approach pioneered by the Soviet Union that relied upon an explosive charge to spray a large area with ‘shrapnel’ in order to ensure the destruction of the satellite. The use of a non-explosive kinetic kill vehicle requires an advanced and highly accurate radar tracking capability in order to guide the kinetic warhead into the target at such high speeds – equivalent in difficulty to reliably striking a bullet in mid-flight with another bullet. This suggests that China’s space-tracking capabilities may be far more advanced than previously thought and,
if China is able to guide a kinetic kill vehicle into a satellite, it is likely that Beijing is, or is not far from, mastering the ability to track and intercept missiles or warheads traveling through the same medium.
..In recent years, China has possessed two or three dozen missiles capable hitting targets in North America. These numbers might be successfully intercepted by even an initially modest US anti-missile system with the necessary architecture. As a result, Beijing would be deprived of its minimum deterrence option, which it obtained in the early 1980s.
The Chinese could avoid that development if they slowly build-up their strategic nuclear forces to a level where they could saturate the American defences.
That build-up might be quite significant. In order to maintain assured penetration even through limited defences with a hundred interceptors, China would need up to 200 strategic warheads deliverable to North American targets. In other words, Beijing may have to increase its minimum strategic forces ten-fold.