The U.S. envoy to multilateral talks on North Korea disarmament could return to Beijing this weekend to meet his North Korean counterpart for talks on ending Pyongyang's nuclear program, a U.S. official said Thursday. The official told Reuters on condition of anonymity that the United States did not know whether the North Korean official, Kim Kye-gwan, would agree to go to Beijing for such talks with U.S. Assistant Secretary of State Christopher Hill. U.S. Secretary of State Condoleezza Rice hinted at progress toward ending Pyongyang's nuclear ambitions during a trip to South Korea, China, and Japan this week, saying she had “constructive discussions” with Chinese President Hu Jintao in Beijing on Wednesday. North Korea agreed to abandon all nuclear weapons and associated programs in exchange for diplomatic and economic benefits under a 2005 six-nation agreement. But implementing the deal between the two Koreas, the United States, China, Japan, and Russia has stalled since Pyongyang's failure to produce a declaration of all its nuclear programs by the end of last year.