The Air Force received its last batch of three F-15K fighters Wednesday from Boeing in the United States under the 40-plane first-phase F-X program to introduce 120 high-end multi-role combat aircraft, Air Force officials said.>> With this latest addition the Air Force has a total of 39 F-15K aircraft, since a unit crashed in the waters off Pohang, some 320 kilometers southeast of Seoul, during a night mission in June 2006.>> The three F-15Ks were delivered to the Air Force's 122 squadron of the 11th Fighter Wing based in Daegu, they said.>> With the gradual delivery of F-15Ks since October 2005, a F-15K squadron has been fully operational since July 1. Another squadron will enter service early next year after pilots undergo related training programs,'' an Air Force spokesman said.>> In 2002, Boeing's F-15K Eagle was selected for the 40-plane, $4.2 billion first phase of the F-X project. South Korea signed with Boeing over the $2.3 billion, 21-plane second phase F-X program early this year. The U.S. aircraft giant is to hand over the aircraft between 2010 and 2012 under the contract.>> The F-15K is capable of air-to-ground, air-to-air and air-to-sea missions day and night, in any weather conditions. It has a 23,000-pound payload and can fly at a maximum speed of Mach 2.3, with an operational radius of 1,800 kilometers. A single aircraft costs about $100 million.>> Its armament includes Boeing's SLAM-ER air-to-ground precision-strike missiles, Joint Direct Attack Munition (JDAM) bombs, and AIM-9X tactical air-to-air missiles built by Raytheon of the United States.