The United States assured North Korea of "a robust channel" for direct talks if it rejoins six-nation nuclear negotiations, as a senior US envoy was in Pyongyang on Wednesday to try to salvage the stalled international talks. Envoy Stephen Bosworth is on a mission to win North Korea's commitment to return to the negotiations on dismantling its nuclear program. The communist government walked away from the talks earlier this year, angered by criticism of its nuclear and missile programs. A nuclear test soon followed. Bosworth's three-day visit to Pyongyang is the first by a US official since President Barack Obama took office. State Department officials said Bosworth, who arrived Tuesday, would hold high-level talks Wednesday before departing for Seoul on Thursday. They did not say whom Bosworth and his delegation would meet. There is speculation that North Korea would demand Wednesday that the U.S sign a peace treaty with it in return for rejoining the six-party talks, which involve the two Koreas, China, Russia, Japan and the US. The two Koreas have been locked in a truce, without a peace treaty, since the close of the 1950-53 Korean War. Wary of the 28,500 troops Washington has stationed in South Korea, North Korea has long sought a peace treaty with the U.S. North Korea says the lack of a peace treaty is evidence that the US has a "hostile" attitude toward it, and that it needed to develop atomic bombs as a result to defend itself in case the US attacked. "North Korea cannot help but talk about a peace treaty because that's the fundamental reason that they say pushed them to build nuclear weapons," said Chang Yong-seok, an analyst at the Institute for Peace Affairs, an independent think tank in Seoul. U.S. officials say a peace treaty is not on the agenda for Bosworth's trip to the North. However, State Department spokesman P.J. Crowley said Tuesday that it "would not surprise us" if the North raised other issues. "We will make clear to them that should they return to the six-party process and should they reaffirm their commitments" under a 2005 disarmament pact, "then there is available to them a robust channel for bilateral dialogue," he said. The two sides can use that channel to discuss "a wide range of issues," Crowley said. Impoverished, isolated North Korea sees settling diplomatic relations with the US as key to ensuring its own survival, and winning aid needed to rebuild its moribund economy. North Korea has struggled since losing the Soviet Union as a benefactor and suffering a series of natural disasters in the 1990s. Today, North Korea relies on international handouts to feed its population of 24 million. "Their current posture in the world is unsustainable. They continue to struggle to feed their own people. North Korea claims that they have no political prisoners and yet we know they do," Crowley said. This week's talks come after a year of threatening rhetoric and rising tensions on the Korean peninsula. North Korea expelled UN nuclear inspectors, restarted its atomic facilities, test-fired a long-range rocket and ballistic missiles and conducted the nuclear test. But in recent months, the North has reached out to the US and South Korea in an about-face that analysts and officials say shows it is feeling the pain of UN sanctions imposed to punish the North for its nuclear test in May. Since August, the North has freed detained US and South Korean citizens and taken other conciliatory steps, including inviting Bosworth for direct talks. Bosworth is accompanied by the lead US nuclear negotiator, Sung Kim, as well as atomic and Asia specialists from the Defense Department and the White House. The delegation was to return to Seoul on Thursday and then visit China, Japan and Russia to brief them on the talks before returning to Washington.