South Korea's chief nuclear envoy left for Washington on Thursday to coordinate the allies' response to North Korea's nuclear and missile programs in the wake of new sanctions on Pyongyang.

Kim Hong-kyun, special representative for Korean Peninsula peace and security affairs, will visit Washington for three days to hold a series of meetings with U.S. officials on ways to cope with North Korea's security threats.

"We will focus our discussions on our overall approach to changing North Korea's behavior, based on our two governments' common stance of firmly responding to North Korea's nuclear development and provocations," Kim told Yonhap News Agency by phone before boarding his plane.

On Friday, Kim plans to meet with his U.S. counterpart, Ambassador Sung Kim, to share assessments of the political situation on the Korean Peninsula and exchange ideas on ways to ensure the faithful implementation of new sanctions on the North.

Last week, the U.N. Security Council adopted a resolution punishing North Korea for its nuclear test on Jan. 6 and long-range rocket launch on Feb. 7. The measures include mandatory inspections of all cargo going into and out of the North, and a ban on the country's exports of coal and other mineral resources, which serve as a key source of hard currency for the cash-strapped regime.

Since then, Washington and Seoul have also slapped unilateral sanctions on Pyongyang.

Kim dismissed growing speculation that the U.S. has opened up to China's calls for peace treaty talks with North Korea. The two Koreas have remained technically at war since the 1950-53 Korean War ended in a truce, not a peace treaty.

"Now is not the time to talk about dialogue but rather a time to focus on implementing the sanctions," he said. "That's the common stance of South Korea and the U.S."

It is Kim's first trip overseas since taking office last week as the new chief delegate to the now-stalled six-party talks on North Korea's denuclearization. (Yonhap)