The big missile is intended for use against targets over the horizon from the launcher. For this, read planes like the E-3, EA-6B, and KC-10. These are support assets that are often required for successful air campaigns. Going after these planes with fighters has not worked the American fighters are usually flown by better pilots, and usually can shoot down attackers quickly. Just ask the Iraqi and Yugoslavian Air Forces. The SA-20 is intended to be used instead.
The smaller missile, known as 9M96 is capable of engaging incoming ballistic missiles with ranges of 3,500 kilometers (or coming in at 4.8 kilometers per second), but is also quite capable against aircraft. It is also much more compact four 9M96 can be fitted on the same fittings that hold one SA-10 (5V55 or 48N6). The missile is very maneuverable (it can pull 20 Gs) and is also able to reach as high as 110,000 feet. The SA-20 systems reportedly finished tests in February 2004 although entering service was reportedly delayed until 2005 or 2006. It has been offered to China and the UAE, with Iran also reportedly expressing interest.
The United States has not stood still. The MIM-104 Patriot has been repeatedly improved from the versions used in Desert Storm in 1991. The latest version is PAC-3, a hit-to-kill vehicle designed to deal with incoming ballistic missiles. The real surprise is the apparent short range of this missile (15 to 45 kilometers) when compared to the PAC-2 (160 kilometers). Like the 9M96, the PAC-3 is small enough that four missiles can be fitted in place of one PAC-2 or earlier Patriot. The PAC-3 can hit Mach 5, and accelerates like a speeding bullet. It breaks the sound barrier within 20 feet of leaving the launcher.
The PAC-3 is reflective of the fact that the United States views the best anti-aircraft weapon to be another aircraft. F-15s, F-16s, and F/A-18s in American service all carry the AMRAAM missile, which has racked up a very good record in combat against Iraqi and Serbian fighters since 1991. The Patriot has been focused primarily on defending against ballistic missiles. It has proven itself in Desert Storm, and upgraded versions performed well in Operation Iraqi Freedom.
Which system is better? The answer depends on what you are shooting at. Both systems have strengths and weaknesses. The Patriot is combat-proven and in production. In addition to the United States, nine other nations (Israel, Germany, Japan, the Netherlands, South Korea, Greece, Saudi Arabia, Kuwait, and Taiwan) use this missile. Most of these countries have superb air forces, and Patriot is primarily intended for defense against missiles.
On the other hand, the S-400 is designed to be capable against aircraft and missiles. This is important because China and Iran are at a relative disadvantage when it comes to combat pilots, and the 400-kilometer reach of the big missile might help those two countries threaten AWACS aircraft and tankers, and hopefully even the odds. The 9M96 is able to hit both ballistic missiles and aircraft. Russian air defense systems (most notably, the SA-6) have shot down F-16s and even the F-117 something Russian fighters have failed to match. Unlike the Patriot, it has not faced combat, and how well it will really do is open to debate. In the past, Russian systems have been hyped and have not matched up well against Western systems (the T-72 and MiG-29 are major examples).
The Patriot at this point has a slight edge due to its combat record and due to the fact that it is usually complemented by superb air forces. The S-400 has longer range, and some impressive specifications, but it remains to be seen how well it will really work. The big missile has no real Western counterpart. Still, it is a concession that Russias SAMs have been far more successful than its fighters. Harold C. Hutchison (firstname.lastname@example.org)
The Russian S-400 (also known as the SA-20) is one of the newest air-defense systems entering service. This system actually consists of two missiles: A big missile with a range of 400 kilometers, and a small missile with a range of 120 kilometers. The system is an improved version of the S-300 (Cold War era SA-10 Grumble), and uses the same transporters as the Grumble.