Washington has signaled that there could be an opening for talks with Pyongyang if the regime stops its nuclear and ballistic missile testing.

Defense Secretary Jim Mattis said earlier this month: "So long as they stop testing, stop developing, they don't export their weapons, there would be opportunity for talks."

But North Korea, which tested two long-range missiles in July and its sixth nuclear test in September, has shown little interest in dialogue, according to US officials.

Joseph Yun, Washington's top nuclear envoy, told reporters in South Korea earlier this month that there has been "no signal" from the North.

The regime has also ignored Seoul's proposal for military and humanitarian talks.

Chun, the vice minister, is currently on a six-day visit to the US. He is scheduled to hold meetings with Yun and Sen. Ed Markey (D-MA) and deliver a speech at a forum in Washington. He will then fly to New York to discuss North Korean humanitarian aid issues with the United Nations Population Fund and the UN Children's Fund.

Lee is set to arrive in the US Tuesday for a four-day visit to Washington and New York, which will include meetings with Yun, other government officials and experts. 

"It is my first trip to the US since taking office (as the envoy)," Lee told Yonhap News Agency before boarding a flight to the US. "I plan to meet and discuss matters with Special Representative Joseph Yun and officials from the National Security Council, the State Department and the United Nations' Secretariat."

"As I have met up with all the top negotiators for member countries of the six-party talks (except North Korea), I will discuss, based on the previous meetings, what to do next and what to make of today's situation." (Yonhap)