TOKYO: North Korea has halted operations at a nuclear power reactor at the centre of an international row, a move that could let Pyongyang reprocess spent fuel to retract plutonium and boost its nuclear arsenal, a press report said on Sunday. The United States will shortly send Christopher Hill, the assistant secretary of state for East Asian and Pacific affairs, to South Korea, Japan and China for talks to cope with the new development in the nuclear standoff, the Japanese newspaper Asahi Shimbun said. Washington has verified that operations at the five-megawatt reactor in Yongbyon were suspended in April, the influential daily said in a report from Washington quoting sources including US government officials. The US administration reached the conclusion by analysing satellite pictures and estimating temperatures on the walls of nuclear facilities and amounts of steam coming from boilers at Yongbyon, north of Pyongyang, the report said.