South Korea recently revealed that it has been developing a new tank, to be introduced by 2010. Work on the new vehicles has been under way for ten years,has cost $220 million so far, and has been kept sort of secret. The new tank (the KNMBT) would replace the current, 1980s era, K1 tank. The 51 ton K1 is based on the American M1 design, but is somewhat smaller and equipped with the same 105mm gun used by the U.S. M60 tank. The K1 has a 1,200 horsepower diesel, instead of a 1,500 horsepower gas turbine engine in the M1. Production of the K1 ended in 1997, with about a thousand built. There have been some upgrades to the fire control and communications systems, as well as the development of the K1A1, which has the same 120mm gun as the M1, along with other equipment used by the M1, but not the K1. The K1A1 is apparently part of the KNMBT development project, as only two K1A1 prototypes were built, and successfully tested. There were plans to build 300 K1A1s by 2010, but this appears to have changed. The new KNMBT is to have an improved 120mm gun, capable of firing an anti-tank missile, as well as the usual gun munitions. The KNMBT will weigh 55 tons and will outclass anything North Korea, Japan or China have.