Factbox - South Korea joins U.S., allies planning to buy F-35 fighters

WASHINGTON (Reuters) - The United States and its allies plan to buy more than 3,100 new F-35 Joint Strike Fighter warplanes in coming years. Following is a list of the planned purchases, according to data provided by Lockheed Martin Corp, the prime contractor for the $392 billion (237 billion pounds) weapons program, and defence officials in the United States and other purchasing countries. Lockheed is developing three variations for the U.S. military services and eight partner countries that helped fund the plane's development - Britain, Australia, Italy, Turkey, the Netherlands, Denmark, Norway and Canada. South Korea this week said it would join the two other countries outside that group, Israel and Japan, that have already placed orders for the jet. The conventional landing A-model will be used by the U.S. Air Force and most allies; the B-model, which can take off from shorter runways and land like a helicopter, will be used by the U.S. Marine Corps, Italy and Britain; and the C-model, or carrier variant, will be used by the U.S. Navy and Marine Corps. U.S. AIR FORCE The U.S. Air Force plans to buy a total of 1,763 F-35 A-models through 2037. The Air Force is training F-35 pilots and technicians at Eglin Air Force Base in Florida, and recently began night training flights at the base. More than 65 pilots and 400 technicians have been qualified to fly and maintain the jet. The Air Force is also flying jets at bases in Nevada and Arizona. U.S. NAVY Current plans call for the U.S. Navy to buy 260 C-model F-35s, which have longer wings and a special tailhook that allows them to land on aircraft carriers. Lockheed and the F-35 program are testing a redesigned tailhook, with at-sea testing expected later this year. U.S. MARINE CORPS The Marine Corps, the smallest of the U.S. military branches plans to buy 340 F-35 B-models and 80 F-35 C-models to replace its current fleet of F/A-18 Hornets, EA-6B Prowlers, and AV-8B Harrier "jump jets." The Marines are flying jets at an air base in Arizona, and aim to start using the new F-35Bs by mid-2015. However the Pentagon's chief weapons tester and the congressional Government Accountability Office have said those plans may be delayed by the slow pace of Lockheed's work on the needed software. BRITAIN Britain's Royal Air Force and Royal Navy, which have invested $2 billion to help develop the new warplane, plan to buy a total of 138 F-35 B-models. Britain has so far committed to buying 48 of the new planes, and is expected to announce plans for the next 14 jets soon. It has already received three jets. ITALY Italy initially planned to buy 131 F-35 fighters, but curtailed its order to 90 jets in 2012. It is now slated to buy 60 F-35A models and 30 F-35Bs, but budget pressures may force another reduction of up to half of the remaining jets. Italy's state-owned defence company Finmeccanica is one of the subcontractors on the project and its Alenia unit will assemble the planes purchased by Italy, the Netherlands and Norway at large facility in northern Italy. NETHERLANDS The Dutch military initially planned to buy 85 F-35As in coming years, but announced in September that it would buy just 37 jets for now, and could has order more later. It has already received two jets that will be used for training, including one that was used for successful lightning testing. TURKEY Turkey is slated to buy 100 F-35As. In February, a senior Turkish official said Turkey would start its orders with two jets in 2015, with deliveries continuing for 10 years. AUSTRALIA Australia is slated to buy 100 F-35As, and has already purchased 2, the first of which is to be delivered later this year. Australia is expected to announce additional orders later this year. NORWAY Norway plans to buy 52 F-35A fighter jets, and has authorized the purchase of 16 jets, including six that were added in December. DENMARK Denmark was slated to buy 30 F-35As, but it has launched a fresh competition that will not be decided until the end of June 2015. CANADA Canada was to buy 65 F-35 A-model fighter jets for C$9 billion, but announced in December 2012 that it would evaluate all available options for new fighters amid growing controversy about the government's decision to buy the F-35 without an open competition. Canada could decide by June whether to proceed with its planned F-35 buy, or launch a new competition. ISRAEL Israel has ordered 19 F-35 jets, and plans to order up to 75 jets in coming years. A second order could come later this year. JAPAN Japan announced in December 2011 that it was ordering 42 F-35 A-model jets and may order more in coming years. SOUTH KOREA South Korea this week confirmed its plans to buy F-35A jets to replacing its aging F-4 jets. Sources familiar with South Korea's plans said the government plans to spend around 7.34 trillion won ($6.79 billion) for 40 F-35 jets. OTHER COUNTRIES Singapore and Belgium are among other countries that have expressed interest in the Lockheed fighter jet. (Reporting by Andrea Shalal; editing by Andrew Hay)