South Korea handed over control of its forces to the United States during the 1950-53 Korean War to defend against invading troops from North Korea. Peacetime control of its forces was returned in 1994, and South Korea is scheduled to get back operational control in the event of war in December 2015.

But last year, Seoul asked for a delay in the OPCON transfer after North Korea conducted its third nuclear test, saying the security situation on the peninsula was markedly different from when the transfer was agreed upon a few years ago.