Seoul was supposed to regain wartime OPCON in 2015, but the transfer was postponed as the allies agreed in 2014 to a conditions-based handover in the wake of Pyongyang's continued nuclear and missile provocations.

As the two sides push for the transfer, they are expected to speed up their work to verify South Korea's capability to lead combined forces. The allies will first verify Seoul's initial operational capability, then its full operational capability and full mission capability.

At the SCM, the two sides are also expected to coordinate over the proposal to suspend their annual massive Vigilant Ace air exercise that involved some 270 aircraft last year in a show of force against a then provocative Pyongyang.

Speculation has persisted that the exercise will be skipped to boost ongoing diplomacy with the communist regime.

The US Department of Defense has said that the allies agreed to suspend the exercise. But Seoul's defense ministry said the allies just weighed "various ideas, including the (suspension)" in an apparent indication of differences over the fate of this year's exercise.

At the SCM meeting, Jeong and Mattis are likely to discuss cooperation in enforcing the September inter-Korean military agreement aimed at reducing tensions and preventing accidental clashes. Reports have said that Washington may feel uneasy over the fast pace of inter-Korean military cooperation when Pyongyang has yet to take concrete denuclearization steps.

The agreement includes withdrawing some border guard posts, disarming the Joint Security Area in the Demilitarized Zone and setting up air, maritime and ground buffer zones where military exercises are banned. Some measures could affect US forces' military operations in front-line areas. (Yonhap)