Despite North Korean willingness to get rid of its ballistic missile and nuclear weapons program, Japan is moving ahead to expand its ballistic missile defenses. Most of these will be based on the Aegis system, which is normally installed on large (8,000 tons and up) warships. Japan has four of these Aegis anti-missile system destroyers with two more under construction. One of the new Maya class Aegis destroyers was launched in July 2018. It will now have its weapons and equipment installed and be in service by 2020. The second one of these 10,000 ton destroyers is under construction and scheduled to enter service in 2021. The Maya class destroyers are improved versions of the earlier Atago class destroyers. In turn, theses are improved versions of the first four Japanese Aegis-type ships, the Kongo class. The 9,500 ton Kongos were built during the 1990s and modeled on the American Burke class Aegis destroyers. The Kongos had 90 VLS (Vertical Launch System) cells for anti-aircraft/missile missiles as well as ASROC anti-submarine rockets (that carry an anti-submarine torpedo to, in effect, extend the range of the torpedo by 22 kilometers). Japanese Burke type destroyers also carry a five inch gun and eight Japanese designed anti-ship missiles (similar to the American Harpoon). The Maya class has 96 VLS cells (as do Atagos) as well as more advanced electronics that enable the Mayas to link with the U.S. Navy Cooperative Engagement Capability that allows real-time sharing of sensor and other data in real time.
In addition, Japan has ordered two land-based Aegis anti-missile systems but these won’t be in service until 2024. At that point, Japan will have eight Aegis anti-missile systems and could have two more Aegis anti-missile destroyers by 2024 by upgrading the Aegis systems on two of the older destroyers. That depends on whether North Korea continues to be a threat and how much more of a ballistic missile threat China becomes. At the moment North Korea is sounding less cooperative and the Chinese are still a threat.
In 2017, Japan decided it did not need the more expensive THAAD anti-missile system and instead expanded its Aegis anti-missile systems. Japan is installing the two land-based Aegis systems on the main island. That plus the Aegis equipped destroyers armed with the SM-3A anti-missile missile would enable those two land-based Aegis systems to protect all three of the home islands. In addition, Japan has 24 Patriot anti-aircraft missile batteries that can also fire the PAC-3 anti-missile missile. The PAC-3 has one drawback, it only has an effective range of 30 kilometers against incoming missiles. The Aegis SM-3 anti-missile missile has a range of from 700 kilometers (older Block 1) to more than three times that for the later Block II models. This is why two Aegis land-based systems can protect most of Japan (the main island). The Patriot PAC-3 provides local defense for key targets (the capital and major military bases).
The first Aegis Ashore system became operational in 2015 in East Europe and appears to be as reliable as the original ship-based systems. This was what was expected because the East European Aegis had never been to sea. In early 2014 the only land-based Aegis system in existence (in New Jersey) was taken apart, packed into 60 large (18.2 meter/40 foot) shipping containers and sent to Romania where it was put back together and in 2015 was an operational anti-missile system. After that two more ground-based Aegis systems were ordered; one in Poland and one in Hawaii. All three, including new Aegis components for two of them and needed missiles (24 per location) and launching hardware for all of them came out costing $767 million each. Then came the Japanese Aegis Ashore order, which will cost over two billion dollars for each system.
The U.S. has long sought to put anti-missile systems in Eastern Europe to protect against ballistic missile attacks from Iran. Russia has opposed this and sees it as a subterfuge to weaken the effect of Russian ballistic missiles attacking European targets. Most Europeans don’t know what to make of that, but East European countries (like Romania) that spent 1945-89 as involuntary Russian vassal (or “satellite”) states, do see a need for protection from Russian missiles.
So far, Aegis has achieved an 83 percent success rate during live test firings. As a result, many countries want Aegis ABM (Anti-Ballistic Missile) ships for protection from local ballistic missile threats. The Aegis system was designed to operate aboard warships. These are usually cruisers and destroyers that have been equipped with the special software that enables the AEGIS radar system to detect and track incoming ballistic missiles. Currently, the U.S. Navy has about 40 ships with the Aegis anti-missile system. There are over 100 American and foreign warships equipped with Aegis, but less than half of them had the software mods and anti-missile missiles that enable them to shoot down ballistic missiles and low-orbit satellites. Converting an Aegis ship to Aegis ABM costs about $30 million, mainly for new software and a few new hardware items. This is seen as a safe investment and the U.S. expects to see most Aegis equipped ships to be upgraded to ABM versions in the 2020s.
To knock down ballistic missiles Aegis uses two similar models of the U.S. Navy Standard anti-aircraft missile, in addition to a modified version of the Aegis radar system, which can now track incoming ballistic missiles. The anti-missile missile is the RIM-161A, also known as the Standard Missile 3 (or SM-3). It has a range of over 500 kilometers and max altitude of over 160 kilometers. The Standard 3 is based on the anti-missile version of the Standard 2 (SM-2 Block IV). This SM-2 missile turned out to be effective against ballistic missile warheads that are closer to their target, as is its replacement, the SM-6. One test saw a SM-2 Block IV missile destroy a warhead that was only 19 kilometers up. An SM-3 missile can destroy a warhead that is more than 200 kilometers up. But the SM-3 is only good for anti-missile work, while the SM-2 Block IV and SM-6 can be used against both ballistic missiles and aircraft. The SM-2 Block IV also costs less than half what a SM-3 costs. SM-3 is not being replaced by instead constantly upgraded.
The SM-3 has four stages. The first two boost the interceptor out of the atmosphere. The third stage fires twice to boost the interceptor farther beyond the earth's atmosphere. Prior to each motor firing it takes a GPS reading to correct course for approaching the target. The fourth stage is the nine kg (20 pound) LEAP kill vehicle, which uses infrared sensors to close on the target and ram it.