South Korean Vice Foreign Minister Lim Sung-nam headed Friday to Tokyo for talks with his American and Japanese counterparts largely on North Korea.

The significance of security cooperation among the regional powers has grown since the North's nuclear test last week.

The U.N. Security Council is working on a resolution to impose new sanctions on Pyongyang. The three nations are also exploring ways to counter the North's nuclear and missile threats more effectively.

In Tokyo, Lim plans to pay a courtesy call on Japan's Foreign Minister Fumio Kishida later Friday.

On Saturday, he is scheduled to hold a series of bilateral meetings with U.S. Deputy Secretary of State Tony Blinken and Japanese Vice Foreign Minister Akitaka Saiki. 

Lim, Blinken and Saiki will then have a group meeting.

"The issue of responding to North Korea's nuclear test will be the most important focus," a senior South Korean ministry official said.

Seoul, Washington and Tokyo are struggling to elicit Beijing's full support for their efforts to take tough punitive steps against Pyongyang.

Lim is expected to brief Blinken and Saiki on the results of the consultations between the top nuclear envoys of South Korea and China held in Beijing Thursday.

Also to be discussed are regional and global issues such as cyber security and development cooperation, according to the ministry official.

The U.S. deputy secretary, meanwhile, will visit South Korea next week as part of his Asia tour.

During his two-day stay starting Tuesday, Blinken will meet with Foreign Minister Yun Byung-se. (Yonhap)