North Korea's top nuclear negotiator was in Singapore on Monday for a meeting with his U.S. counterpart aimed at breaking a deadlock over how the communist country will account for its nuclear program's hazy past. Kim Kye Gwan flew in from Beijing and left the airport with North Korean officials without speaking to reporters, South Korea's Yonhap news agency reported. Singapore did not immediately issue any statement on Kim's whereabouts. Kim was scheduled to meet with U.S. Assistant Secretary of State Christopher Hill on Tuesday. Hill, who also was to arrive Monday, was to travel later to Beijing to report on the talks.