South Korea is proposing the sale of approximately 500 supersonic trainer jets to the US, whose air force is considering replacing its aging fleet of trainer aircraft.
The US Air Force is expected to make a decision by 2012 on whether to upgrade its T-38 trainer jets or to replace them with new ones.
A team of US inspectors visited Seoul to check the performance of the South Korean-built T-50 trainer jets.
The USAF, which is studying the T-50, Italy's M-346 and the UK's Hawk 128, could buy 300 to 500 aircraft to replace its T-38s.
South Korea launched its T-50 Golden Eagle, jointly developed by Korea Aerospace Industries and Lockheed Martin, in 2005, at a cost of $20m each.