The Korea Times, quoting a senior South Korean procurement official, reports that the air-to-ground missile doesn't fit the aircraft because of a missile design inconsistency.
"To install the JASSMs in both wings of the F-15K, either F-15K's pylon or the JASSM's upper wing should be modified, but it would cost a lot," the official said.
The report said the finding could delay South Korea's project to purchase a standoff missile system.
The Joint Air-to-Surface Standoff Missile is manufactured by Lockheed Martin and is a precision cruise missile with a range of about 230 miles -- less than its German competitor, Taurus System's standoff missile.
South Korean tests indicated the JASSM doesn't fit the F-15K since the missile's upper wing folds only to the left side. Aircraft manufacturer Boeing and Lockheed Martin have been queried about ways to fit the missile onto the aircraft but have not responded, the official said.