UNITED NATIONS -- North Korea removed fuel rods from its nuclear reactor as international pressure mounted on the Communist state to let inspectors verify that no plutonium was being diverted to a weapons program. The Communist North says its nuclear program is peaceful. But its refusal for more than a year to allow full inspections of its nuclear facilities has deepened suspicion that it is developing nuclear weapons. U.S. officials have said they were concerned about the speed with which North Korea was removing the fuel rods. South Korean President Kim Young-sam arrived in Moscow on Wednesday for a visit expected to focus on enlisting Russian support in resolving the crisis. A South Korean special envoy was to leave Thursday for New York for talks with U.S. officials on the nuclear crisis, the South Korean Foreign Ministry said Wednesday. Two Japanese lawmakers will visit the North Korean capital June 14-17 for further talks on the nuclear issue, officials in Tokyo said Wednesday. The International Atomic Energy Agency, a UN nuclear watchdog, reported this weekend that North Korea was unloading spent fuel from the reactor so quickly that within days it may be impossible to determine whether nuclear materials were diverted. "The pace of removal is a concern, but we are hopeful we can find a diplomatic settlement," Pentagon spokeswoman Kathleen deLaski said Tuesday. U.S. officials say the five-megawatt reactor at Yongbyon could produce enough plutonium to make several atomic bombs. UN Diplomats sounded troubled on Tuesday: "There is no smoking gun, but there is circumstantial evidence that points in one direction and that is not a direction that makes the Security Council comfortable," said Sir David Hannay, Britain's ambassador to the UN.White House Press Secretary Dee Dee Myers said the United States was very concerned about the situation and that it would be up to the agency to determine "whether the continuity of safeguards has been broken."Myers said President Bill Clinton spoke with President Kim of South Korea for about 20 minutes on Monday evening. They talked after the UN Security Council adopted a non-binding statement urging North Korea to stop refueling its reactor in a way that could destroy evidence of its nuclear intentions. The Security Council's statement made no mention of economic sanctions, but they are considered likely if North Korea does not allow inspectors to carry out their work. North Korea has said it would regard any economic sanctions as an act of war. At the UN, Hannay said a vote on sanctions "depends on the North Koreans. They have a choice." On Tuesday, the agency sent a letter to North Korea detailing ways the refueling could be monitored, sources at the agency said. A North Korean proposal would not allow inspectors to verify the location of fuel rods, needed for future measurements, the sources said. North Korea, meanwhile, launched another in a series of missile tests Tuesday, Pentagon officials said. The development did not raise concern among military officers, they said.