The department also pledged to continue to support the KF-X project "to the maximum extent possible."

"At this point, the United States is confident Lockheed Martin and the Republic of Korea currently have the necessary approvals to move forward on the KF-X program," David McKeeby, a spokesman for the U.S. Department of State's Bureau of Political-Military Affairs, told Yonhap News Agency.

As the program develops, the U.S. expects that export licenses will be periodically amended as the program matures and becomes better defined, he added.

"The key takeaway here is that the United States will support the KF-X indigenous fighter program to the maximum extent possible. We will continue to work closely with Lockheed Martin to ensure continued strong and meaningful support for KF-X," the spokesman said.

Earlier in the day, South Korean officials said that the U.S. government gave Lockheed Martin export licenses for the planned transfer to Seoul of 21 technologies necessary for the fighter project and that the defense firm informed Seoul of the approval.

The U.S. approval of the technology transfer laid to rest growing speculation that Washington might be reluctant to approve the technology transfer. Such speculation arose after reports that the U.S. decided not to approve the transfer of an additional three technologies after refusing to transfer four technologies earlier this year.

Under the $15.7 billion program, South Korea plans to produce 120 indigenous combat jets by 2025. In an offset deal linked to South Korea's purchase of 40 units of Lockheed Martin's F-35 Lightning II fighters last year, the U.S. company had offered to provide 25 technologies for the local program.