January 24, 2015: Russia recently revealed that it had sold China six battalions of its new S-400 anti-aircraft missile system. Each battalion will cost $500 million and includes training as well as spare parts and additional missiles. Each S-400 battalion has eight launchers, each with two missiles, plus a control center and radar and 16 missiles available as reloads. All equipment is mobile. S-400 is also known as the S-300PMU-3, SA-21 or Triumf and was renamed S-400 because it turned out to be far more than just another upgrade of the S-300 and was considered sufficiently different to warrant a name upgrade. Russia deployed its first S-400 battalion in 2010, around Moscow.

The S-400 is similar to the U.S. Patriot and pays particular attention to electronic countermeasures that the Americans might have, or be developing. The missiles are also physically larger and have longer range as well as being very expensive. Russia began seeking export sales in 2011. The S-400 missiles weigh 1.8 tons each and are 8.4 meters (26 feet) long and about 50cm (20 inches) in diameter. The missiles have a range of some 400 kilometers, and can hit targets as high as 31,000 meters (100,000 feet). The missile has a 145.5 kg (320 pound) warhead. The target acquisition radar has a range of 700 kilometers. The missiles are built to last for 15 years before needing refurbishment.

The S-400 has over twice 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 are within 60 kilometers of an S-400 launcher. 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 types of missiles, one of them being smaller, with a shorter range (120 kilometers). These are deployed four to a launcher, like all other S-300 systems. The larger missile actually has two versions, one with a range of 250 kilometers and a more expensive one with a range of 400 kilometers. The S-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.

Russia plans to buy up to 200 launchers (each with two or four missiles) by 2015, and phase out the older S-300 and S-200 systems. This would mean deploying at least 18 battalions by 2017 and 56 by 2020 (or organized into 28 battalions containing two battalions each).  China plans to deploy its first S-400 battalion opposite Taiwan. That one battalion can cover all Taiwanese air space. The next battalions will be deployed to deal with Japan, South Korea and Vietnam.