July 9, 2008: China has upgraded its anti-aircraft missiles along its southern coast (facing Taiwan) from S-300PMU1 and S-300PMU2 systems to the S-300PMU3. This model has been renamed the S400 because of the large number of improvements.

The S-300/400 system is roughly equivalent to the U.S. Patriot system, and was originally known as the SA-10 to NATO, when the system first appeared in the early 1980s. There have been many upgrades since. The missiles weigh 1.8 tons each and are 26 feet long and about 20 inches in diameter. The missiles have a range of some 200 kilometers (400 kilometers for the S-400) and can hit targets as high as 100,000 feet. The missile has a 320 pound warhead. The target acquisition radar has a range of 700 kilometers. The Taiwan Straits are only 180 kilometers wide.

The S-400 has over five times the range of the U.S. Patriot, weighs twice as much and claims the ability to detect stealthy aircraft. The S-400 also has an anti-missile capability, which is limited to shorter range (3,500 kilometers) ballistic missiles. That would mean a warhead coming in at about 5,000 meters a second (the longer the range of a ballistic missile, the higher its re-entry speed.)

The S-400 system actually has two missiles, one of them being a smaller, shorter range (120 kilometers) one. The S-300/400 has no combat experience, but U.S. intelligence believes that the tests these systems have undergone indicate it is a capable air defense weapon. Just how capable won't be known until it actually gets used in combat.

The first S-400 battalion (four launchers and a radar) was installed outside Moscow last Summer. Russia plans to buy up to 200 launchers (each with four missiles) by 2015, and phase out the older S-300 and S-200 systems. China, a major user of the S-300, is a major export customer for the new system. South Korea is developing their own version of the S-400, via s special deal with Russia.