Due to serious technical and budgetary problems South Korea may not go for fifth-generation stealth fighter planes originally conceived under the KF-X Plan.In a detailed interim report submitted by Weapon Systems Concept Development and Application Research Center to Defense Acquisition Program Administration (DAPA) it has been highlighted that currents plans needs some fundamental changes to make it more feasible.

Under the original plan (KF-X program) it was aimed to produce around 120 fifth-generation fighters stealthier than Dassault's Rafale or the Eurofighter Typhoon, though not as much as stealthier as Lockheed Martin's F-35 Lightening II.
After through assessment, the program has been found technically and economically nonviable in its present form. Accordingly to an earlier feasibility report conducted in 2007 it was concluded that the KF-X project would cost at least $10 billion. In return only $3 billion in economic benefits were expected.

Convinced that it will not be wise to go alone on this project Weapon Systems Concept Development and Application Research Center is considering partnerships with foreign players. It is expected to report on this at the end of this year. According the report KF- X will be an F-16 Block 50 level multi-role fighter jet with an engine thrust of 50,000 pounds. Currently twin-engine system is preferred over one engine.

Fighter plane was expected to be fitted with an active electronically scanned array (AESA) radar, an electronic warfare suite and infrared search-and-track system, and data link systems fit for a network-centric environment .In the first phase of plan around 120 new aircraft will be produced after 2010 to replace older F-4s and F-5s. In the second phase around 130 aircraft is planed to be produced after the first phase aircrafts will become operational..

Korea s also expected to delay the purchase of foreign stealth fighters under the F-X multi-phase fighter procurement program. Under the original plan Korean was expected to buy around 120 high-end fighter jets by 2020 in an effort to modernize the Air Force's fighter fleet

Foe the third phase of the program, expected to begin by 2012, Korea is expected to focus on acquiring fifth-generation stealth fighters. The Lockheed Martin-built F-35 is considered as front-runner for this phase.