The top U.S. diplomat on Asia was due in Seoul on Sunday for discussions likely to focus on North Korea amid concerns the communist nation could attempt provocations in anger over planned military exercises in the South.

Assistant Secretary of State Daniel Russel, who accompanied Deputy Secretary of State William Burns on a trip to China and Japan, is scheduled to meet with South Korean Deputy Foreign Minister Lee Kyung-soo to brief him on the results of Burns' discussions in Beijing and Tokyo.

North Korea is expected to be the main point of their discussions.

Pyongyang has stepped up conciliatory gestures in recent weeks, proposing that the two Koreas halt slandering each other and demanding the South call off a set of planned military exercises with the United States. The charm offensive has spurred speculation that it might be an attempt to build justification for hostilities against Seoul.

The South has rejected the North's demand, saying it will hold the drills as planned.

Russel is also expected to reiterate the need to improve relations between South Korea and Japan.

Frayed relations between Seoul and Tokyo have been a cause for concern for the United States as Washington seeks to build strong, three-way security cooperation with the two Asian allies in an effort to keep a rising China in check. (Yonhap News)