Japan has shown reluctance to accept a proposal by South Korea to declare a formal end to the Korean War as a way to entice North Korea into negotiations on denuclearization, diplomatic sources said Saturday, revealing gaps in the efforts also involving the United States.

Tokyo has been concerned that such a preceding conciliatory move would complicate its position, with the issue of past abductions of Japanese citizens by North Korea remaining unresolved as Pyongyang continues to pursue its nuclear and missile development programs in defiance of U.N. Security Council resolutions, the sources said.

The United States and North Korea remain technically in a state of war as the 1950-1953 Korean War — in which U.S.-led U.N. forces fought alongside the South against the North, backed by China and the Soviet Union — ended in a ceasefire, not a peace treaty.