North Korea appeared set Monday to miss a year-end deadline to disable a key nuclear reactor and declare all its nuclear programs, key components of its disarmament as agreed in an international accord. The communist country promised to disable its main nuclear reactor at Yongbyon, north of Pyongyang, and give a full accounting of its nuclear programs by Dec. 31 in return for energy aid and political concessions. The US says it is disappointed, but the countries that negotiated the accord have not indicated what, if any, sanctions North Korea would face over the delay. The North shut down the plutonium-producing facility in July and disablement work is under way in cooperation with US experts. But diplomats, including South Korean Foreign Minister Song Min-soon, have said the North is likely to miss the year-end deadline for disablement because a key step - removing fuel rods from the reactor - could take several months.