South Korea is spending $1.3 billion to upgrade its three Patriot battalions to handle the PAC-3 anti-missile missile (and buy lots of PAC-3s). The current version of the original Patriot missile design (MIM-104E PAC 2) cost $2 million to $4 million each (depending on options and accessories) and can be used against aircraft and missiles. The PAC-3 (MIM-104F) anti-missile missile can only be used against missiles and can cost up to $3 million each. The PAC-3 missile is smaller than the anti-aircraft version (PAC-2), thus a Patriot launcher can hold sixteen PAC 3 missiles, versus four PAC-2s. A PAC 2 missile weighs about a ton, a PAC-3 weighs about a third of that. The PAC-3 has a shorter range (about 20 kilometers) versus 70 kilometers for the anti-aircraft version. PAC-3 can also take down longer-range ballistic missiles. The Patriot radar can detect targets out to a hundred kilometers.
In late 2013 South Korea bought another 112 PAC-2 (MIM-104E) Patriot anti-aircraft missiles. South Korea hasn’t had to buy Patriot missiles in a long time. That’s because back in 2008, South Korea received a billion dollars’ worth of second-hand German Patriot anti-aircraft missiles. The Germans didn't need as many Patriot batteries since the Cold War ended in 1991. So they sold South Korea all the equipment for three Patriot battalions and several hundred PAC 2 missiles. South Korea wanted the Patriot in part to improve their defenses against North Korean ballistic missiles. The PAC-2 can knock down the SCUD type missiles that North Korea has hundreds of. Patriot battalions have 12-24 launchers (in 3-6 batteries). Each battery is manned by about a hundred troops and contains a radar plus four launchers. A battery can fire PAC-3s only after some software and hardware upgrades.
Meanwhile, some of the Patriot missiles bought from Germany are now reaching the end of their useful lives. To deal with that South Korea will use the U.S. Army re-certification program for Patriot missiles, which means missiles can now be kept in service for up to 45 years via refurbishment. This is a big deal because all munitions have a specific shelf life (how many years they can remain in storage but still will function if used). But with missiles you can often extend the original “shelf life” with new components and refurbishment techniques.
Introduced in 1981, the Patriot missiles originally had a shelf life of 15 years. As that limit approached, the existing missiles were examined and it was determined that those that had various age-sensitive components (batteries, rocket motor, and most electronics) replaced before they reached their useful life could be re-certified to last another 15 years. Now older missiles have again been re-certified and some of the 100,000 missiles built since the 1980s can be kept around for 45 years. The refurbishment also includes using new technology to accurately measure age-related decay in many components. This is an important aspect of being able to extend shelf-life in missiles and aircraft.
When elderly components are replaced it is often with improved versions of the aging component. This is particularly true with the electronics, which are most subject to upgrades. This continuous upgrading makes it worthwhile to keep older Patriot missiles in service over a long period of time. Most missiles are never fired and are eventually deemed too unreliable for use and are taken apart for scrap and reusable spare parts. About five percent of the Patriot missiles built have been used for testing and less than a hundred fired in actual combat. The missiles are stored and fired from a protective container, which can be plugged into diagnostic equipment for regular testing. In addition to the United States, another twelve nations use Patriot.
Before Patriot South Korea had used the older Hawk missile system. While Hawk has been upgraded over the last half century, South Korea has gone beyond that. Back in 2011, South Korea introduced a locally designed and produced Iron Hawk II anti-aircraft missile system. This replaced three existing U.S. Hawk missile battalions. Iron Hawk II is mobile, with the radar and launchers carried on trucks. Each launcher truck has six missiles in sealed storage/firing containers. The original Hawk did not use the container system. Hawk missiles have a max range of 40 kilometers and a max altitude of 15,000 meters (46,500 feet). The search radar (with a max range of 100 kilometers) guides missiles part of the way before the missiles' own guidance system takes over for the final approach. South Korea had help from Russia in developing the AESA search radar and the Iron Hawk missiles. Because the main military threat, North Korea, is right next to South Korea, Hawk range is not a big issue.