December 30, 2023: Russia’s most modern air defense system is the S-400. The current version of the S-400 has a battery radar that can detect targets up to 400 kilometers away and launch S-400 missiles at targets up to 75 kilometers distant. Unfortunately, most modern jet combat aircraft carry an array of countermeasures to defeat missiles fired at them from the ground or other aircraft. In addition to missiles fired from the ground, warplanes also have to worry about missiles fired from jet fighters. These are often more effective. At the same time, Russia has found that their S-400 missiles are more effective against ground targets, which can be hit at distances of up to 350 kilometers. Russia developed a S-400 system called the 48/6DM that is effective against air targets but can also accurately hit ground targets up to 230 kilometers away. The warhead weighs 180 kg and contains enough explosives to be effective against ground targets that are usually major Ukrainian cities. These places are often defended by American Patriot, which often succeed in intercepting Russian air defense missiles used against ground targets.

The U.S. Navy has also modified its SM series of air defense missiles to hit surface, as in ships, targets. These missiles could also be used against ground targets not too far from the shoreline. The 1.3 ton SM-6 warhead weighs less than a hundred kg. That’s not a lot of explosives, but that warhead is accompanied by a large portion of the missile body which adds to the destructive effect. What makes that possible is that the missile hits the targets at speeds similar to rifle bullets. When using a high speed missile against a warship, the damage was extensive. The Navy verified this during a SINKEX, or inking exercise where a retired warship is used as the target. In this case the target ship was a recently retired 4,000-ton frigate. The warhead traveling at high speed did enough damage to render the target ship unable to move or fight. This is what would happen to an enemy ship hit with an SM-6 missile in wartime.

This was consistent with results from earlier SINKEX tests where the older SM-2 missile, which entered service in 1980 and was also designed for use against surface targets as well as aircraft. The max range of an SM-6 against a surface ship is 240 kilometers. The longer range and higher speed of the SM-6 make it particularly effective against other ships.

The SM-6 is basically the existing SM-2 anti-aircraft missile with the more capable guidance system of the AMRAAM air-to-air missile, as well as general improvements in the electronics and other components. The SM-6 is a 1.5 ton, 6.55 meter long, 533mm diameter missile. It has a max altitude of 33 kilometers, or 110,000 feet.

The older SM-2 is a 1.35 ton, 8 meter long missile with a max range of 190 kilometers and max altitude of 24.4 kilometers, or 80,200 feet. The main change for the SM-6 is the guidance system which is self-contained and will seek out any target it comes within range of. The SM-2 uses a semi-active guidance system, which requires that a special targeting radar light up the target with a radar beam, which the SM-2 guidance system detects and homes in on. The active guidance system of the SM-6 is harder to jam and can home in on targets beyond the range of targeting radars. The SM-6 can attack anti-ship missiles as well.

The SM-6 took nine years to develop and has been in production since 2011, with plans to obtain up to 1,800 missiles at a cost of $4.3 million each. SM-6 will replace many of the SM-2 missiles carried by American and Australian warships. Navy anti-aircraft missiles, including the SM series, have long been used as anti-ship weapons.

Meanwhile, the navy has been continuing years of improvements in the Aegis radar and fire control system that controls SM-2, SM-6, and the smaller SM-3 anti-missile version. The SM-3 can destroy ballistic missiles and low orbit satellites. Aegis equipped ships began getting version 4.0 of the Aegis anti-missile software in 2013 and the 5.0 upgrade made the anti-missile capabilities a standard feature of Aegis software. New destroyers are having anti-missile Aegis software installed as standard equipment. Much of the anti-missile capability of the original Aegis anti-aircraft system came from upgrades to the Aegis software.

The Aegis anti-missile system has had a success rate of over 80 percent in knocking down incoming ballistic missile warheads during test firings. To achieve this, two similar models of the U.S. Navy Standard anti-aircraft missile are in service, in addition to the Aegis radar system modified to track incoming ballistic missiles version.

The RIM-161A, also known as the SM-3 or Standard Missile 3, has a range of over 500 kilometers and max altitude of over 160 kilometers. Standard 3 is based on the anti-missile version of Standard 2 Block IV. This SM-3 missile has a shorter range than the SM-2, which can destroy a warhead that is more than 200 kilometers up. The SM-3 is optimized for anti-missile work, while the SM-2 Block IV was designed to be used against both ballistic missiles and aircraft. The SM-2 Block IV also costs less than half of what an SM-3 costs. So going after aircraft with SM-3s is discouraged unless absolutely necessary.