U.S. special envoy for North Korea policy Stephen Bosworth will fly to Pyongyang Tuesday from South Korea's Osan Air Base.

During his three-day stay there, he will meet with North Korean Vice Foreign Minister Kang Sok-ju and urge the North to return to the six-party nuclear talks and implement agreed denuclearization measures.

Prospects are not bright, however, as Pyongyang is expected to instead stress the establishment of a peace regime as the key agenda for the meeting.

Attention lies on whether the U.S. will offer a new bargaining chip for North Korea's return to the six-way talks or whether the North will make a surprise proposal to keep the U.S. at the negotiating table.

A senior South Korean official forecasts that if the North declares a return to the six-way process, the normalization of Pyongyang-Washington ties could be discussed.