The defense acquisition agency "is now preparing documents to be handed in to Cheong Wa Dae," the official said.

   The Air Force acquisition project, Korean Fighter Experimental (KF-X), has come under fire after findings that the U.S. did not allow exports of four major technologies promised for the South Korean project in a decision made in April.

   Under the project to build homegrown combat jets, DAPA agreed with Lockheed Martin to obtain 25 kinds of fighter jet technologies from the U.S. firm in a sideline deal clinched when DAPA purchased 40 F-35A combat planes a year earlier.

   Including the more than 8 trillion won ($6.7 billion) expected for research and development, the project is presumed to cost nearly 18 trillion won to produce the new fleet of 120 combat jets.

   Earlier this week, DAPA belatedly confirmed that the U.S.

government refused to grant export licenses on four of the 25 Lockheed Martin technologies promised last year on account of the country's technology protection policy.

   Final export permission on the rest of the 21 technologies is also pending at the U.S. Department of State although DAPA said they are sure to win the approval.  

   The announcement increased skepticism over the fate of the much-trumpeted project, with South Korea missing the four essential technologies, including those on integrating active electronically scanned array radar and other sensors into fighter jets' mission computers.

   The KF-X project was launched to replace 120 aging units among the Air Force's some 400 combat planes with locally made aircraft starting in 2025.

   The focus of the presidential probe will reportedly focus on the background of DAPA's unsuccessful transaction with Lockheed Martin, as well as the design of the KF-X project.

   "We plan to draw up related documents and submit them to Cheong Wa Dae today," a DAPA official said. (Yonhap)