Former President Roh Moo-hyun and then-U.S. President George W. Bush speak during a press conference following their meeting in Washington in this May 15, 2003, file photo. In 2006, the two leaders agreed on the basic principles and guidelines for the transfer of wartime operational control, or OPCON, from Washington to Seoul. Korea Times file

Talks on transferring wartime operational control, also known as OPCON, from the United States to South Korea remain a key issue in the decades-long bilateral alliance, which has been marked by periods of progress and setbacks.

Elbridge Colby, the nominee for undersecretary of defense for policy at the Pentagon, reignited the debate on wartime operational control transfer during his confirmation hearing on Tuesday (local time). He said that he would "review this delicate issue carefully," adding that he "supports efforts to bolster South Korea's role in the alliance."

OPCON refers to the authority to command military forces during wartime. South Korea initially transferred its operational control to the United Nations Command (UNC) during the 1950-53 Korean War.

After the war, in 1978, the establishment of the South Korea-U.S. Combined Forces Command (CFC) shifted this authority from the UNC to the CFC, which is led by the commander of U.S. Forces Korea (USFK).

Seoul's efforts to regain operational control date back to the 1980s.

Former President Roh Tae-woo pledged to get the U.S. to transfer OPCON as part of his campaign promises. This marked the beginning of South Korea's persistent efforts, under Roh and his successor Kim Young-sam, to request the return of OPCON.

As a result, in December 1994, South Korea's Joint Chiefs of Staff regained peacetime operational control.

However, this was not a complete transfer of operational control, as wartime OPCON remained under the authority of the USFK commander.

The push for full OPCON transfer gained momentum during the liberal Roh Moo-hyun administration. Through discussions with the George W. Bush administration, the two sides agreed to complete the transition of wartime operational control to Seoul by April 2012.

However, that plan faltered, particularly after North Korea's second nuclear test in 2009 and heightened tensions on the Korean Peninsula. Following Pyongyang's continued provocations, the transition deadline was postponed under the former Lee Myung-bak and his successor Park Geun-hye to late 2020.

Talks regained momentum when the progressive Moon Jae-in administration took power, with Moon pledging to complete the OPCON transfer by the end of his term in 2022. The allies established a three-phase verification process: initial operational capability, full operational capability and full mission capability.

The incumbent Yoon Suk Yeol administration reaffirmed his predecessor's plan in general but has yet to take concrete steps toward its implementation.