South Korea and the United States agreed Tuesday to step up joint efforts to prepare for "all possible scenarios" associated with North Korea, according to a senior South Korean official.

In high-level strategic talks here, the allies noted the possibility that North Korea will take additional provocative steps due to possibly increased instability following the execution of Jang Song-thaek, who held the No. 2 post in the North Korean leadership.

"Accordingly, (the two sides) agreed to the need to further bolster their joint defense posture on the basis of a robust alliance and prepare thoroughly for all possible scenarios," Vice Foreign Minister Kim Kyou-hyun told reporters, emerging from a meeting with American counterpart William Burns at the State Department.

The allies hold such a high-level consultations on a regular basis to discuss regional and global issues.

Tuesday's meeting between Kim and Burns was arranged before the news of the execution of Jang.

"The two nations agreed to endeavor to encourage relevant parties in the region and the international community to make helpful and necessary efforts to maintain peace and stability on the Korean Peninsula," Kim said.

In diplomacy, parties involved in the security of the peninsula usually refer to the two Koreas, the U.S., China, Japan and Russia, which are the members of the now-suspended six-way talks on Pyongyang's nuclear program.

Asked about security cooperation among South Korea, the U.S. and Japan, Kim said all hold the view that the Seoul-Washington alliance and Seoul-Tokyo ties are key factors in the peace and security of Northeast Asia.

"We exchanged opinions on how to do (on the matter) down the road," Kim said. He did not elaborate.

Kim arrived in Washington on Sunday for a four-day stay. On Monday, he met with some Korea experts here. (Yonhap News)