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. The nuclear standoff began in late 2002 after the US accused the North of seeking to secretly enrich uranium in violation of a 1994 disarmament deal. In late 2003, the North began negotiations over its nuclear program with the US, China, Japan, Russia and South Korea in the so-called six-party talks, which eventually led to its disarmament commitments this year. North Korea conducted its first nuclear test, an underground blast, in October 2006, adding urgency to the talks. Expectations that the North would fail to deliver the promised statement on time have risen in recent weeks. The country raised eyebrows last week when a North Korean official indicated that it would slow its disablement work because it was dissatisfied over the delivery of aid to the North so far. US officials say they are disappointed about North Korea's delay in meeting its commitments. "It is unfortunate that North Korea has not yet met its commitments by providing a complete and correct declaration of its nuclear programs and slowing down the process of disablement," the State Department said in a statement Sunday. "We urge North Korea to deliver a complete and correct declaration of all its nuclear weapons programs and nuclear weapons and proliferation activities and complete the agreed disablement," the statement said. The reasons for the delay in declaring the nuclear programs appear related to the country's suspected uranium enrichment program and differences with Washington over how much plutonium it has produced. Song, South Korea's top diplomat, said Thursday that more consultation was required on the alleged uranium enrichment program, while a Japanese newspaper reported that Pyongyang and Washington disagree on the plutonium issue. The Tokyo Shimbun quoted unnamed US and North Korean officials Thursday as saying the North has told the US it has produced about 30 kilograms of the nuclear material, considerably less than US estimates of more than 50 kilograms.