May 2001:                   North Korea threatens to pull out of the 1994 Agreed Framework, saying the U.S. has failed to live up to its obligations under the agreement.

June 2001:                    International Atomic Energy Agency (IAEA) unable to verify that North Korea is not diverting nuclear material for military purposes, as North Korea has not provided the inspectors with sufficient access.

March 2002:                President George W. Bush does not certify North Korea's compliance with the Agreed Framework, but sends fuel oil to Pyongyang under a waiver.

October 2002:              U.S. claims that North Korea acknowledges a secret uranium enrichment program, prompted by U.S. intelligence indicating North Korea was trying to acquire large amounts of high-strength aluminum, useful in equipment to enrich uranium.

U.S. intelligence reportedly concludes that Pakistan was a major supplier of critical equipment to North Korea's newly revealed enrichment program.

November 2002:          Korean Peninsula Energy Development Organization (KEDO) decides to suspend heavy fuel oil shipments to North Korea until North Korea takes steps to dismantle its nuclear program.

U.S. tells Pakistan that inappropriate contact with North Korea will have consequences.

December 2002:           North Korea reportedly succeeds in purchasing from China 20 tons of tributyl phosphate (TBP), which is used to extract plutonium from spent reactor fuel.

North Korea decides to lift the freeze on its nuclear facilities and orders IAEA inspectors to leave the country.

IAEA announces North Korea moved 1,000 fresh nuclear fuel rods to a storage facility at the Yongbyon reactor site.

President Bush identifies North Korea as a key threat to the U.S. and its allies in a National Security Directive on missile defense.

January 2003:               U.S. agrees to direct talks with North Korea to resolve questions about its nuclear program.

North Korea announces it is pulling out of the Nuclear Non-Proliferation Treay (NPT) and rebuffs demands that it allow a return of U.N. inspectors.

U.S. indicates it would consider energy aid to North Korea if it abandons its nuclear weapon program.

North Korea pledges to South Korea not to produce nuclear weapons.

U.S. spy satellites see trucks in North Korea that appear to be moving 8,000 spent fuel rods from storage.

February 2003:             North Korea announces it has restarted its nuclear facilities.

IAEA declares North Korea in non-compliance with its inspection obligations and sends the issue to the U.N. Security Council.

U.S. spy satellites show a steady stream of activity around North Korea's plutonium reprocessing plant.  The activity indicates preparation to activate the facility.

March 2003:                U.S. Assistant Secretary of State James Kelly estimates North Korea could be months, not years, from producing highly-enriched uranium (HEU).

North Korea appears to be having trouble restarting its plutonium processing plant.

April 2003:                   U.S., Britain and France fail to induce the U.N. Security Council to criticize North Korea's pursuit of nuclear weapons, due to Russian and Chinese opposition.

During three-way talks with China and the U.S., a North Korean official says North Korea has nuclear weapons, and that most of the 8,000 spent fuel rods have been reprocessed.

U.S. rejects North Korea's proposal to end its nuclear weapon program only after receiving U.S. concessions.

May 2003:                   South Korean official says the U.S. has a satellite photo showing smoke coming from radiation and chemical labs at Yongbyon (signaling the site may be reprocessing spent fuel rods).

North Korea nullifies a 1992 agreement with South Korea to keep the peninsula free of nuclear weapons.

President Bush and South Korean President Roh Moo-Hyun vow not to "tolerate nuclear weapons in North Korea," and threaten "further steps" if North Korea continues its nuclear program.

Japan cracks down on companies suspected of aiding North Korea's uranium enrichment and missile programs.

June 2003:                    After a visit to North Korea, Congressman Curt Weldon says North Korea admits having nuclear weapons and plans to build more.

According to a U.S.-South Korean joint statement, U.S. troops will withdraw from the Demilitarized Zone (DMZ) in a phased redeployment.  No precise schedule is announced.

North Korea announces plans to build nuclear weapons in an attempt to decrease the size of its conventional military.

The C.I.A. reportedly believes that North Korea is developing technology to make nuclear warheads small enough to fit on missiles.

July 2003:                     U.S. reportedly believes North Korea has begun to process spent fuel rods.

South Korean news indicates North Korea claimed to have restarted the five MW(e) reactor at Yongbyon, and to have resumed construction on two other reactors frozen under the Agreed Framework. 

North Korea says it finished producing enough plutonium from the 8,000 spent fuel rods for six bombs, and that it intends to weaponize the material quickly.

South Korean intelligence confirms North Korea has performed 70 high explosives tests.

IAEA declares North Korea "the most immediate and most serious threat to the nuclear nonproliferation regime."

August 2003:                First six-party talks with U.S., China, South Korea, Russia and Japan; North Korea reportedly announces that it intends to test a nuclear weapon.

September 2003:          A U.S. official says activity at Yongbyon appears to have halted.

October 2003:              New intelligence reportedly estimates that North Korea may have produced one, two, or more new nuclear weapons.

U.S. reportedly says it will give a written guarantee, to be signed by the 6 nations involved in the negotiations, not to attack North Korea if it takes steps toward abandoning its nuclear weapon program.

A German national is charged with exporting aluminum tubing for North Korea=s uranium enrichment program.

November 2003:          C.I.A. tells Congress that North Korea can probably turn nuclear fuel into a functioning weapon without performing a full nuclear test.

North Korea says it would give up its nuclear weapons, cease testing and exporting missiles, and submit to international inspections in exchange for a written security guarantee, economic compensation, and a promise by the U.S. not to hinder its economic development.

December 2003:           All work on the nuclear power project in North Korea, promised under the 1994 Agreed Framework, is suspended for one year.

North Korea says it will freeze its nuclear facilities if the U.S. removes it from the U.S. list of terrorism-sponsoring countries, lifts sanctions and provides energy aid.

North Korea reportedly rejects a U.S. proposal for verifiable and irrevocable dismantlement of North Korea's nuclear program in return for security assurances.

January 2004:               U.S. delegation visits Yongbyon, where it is shown what North Korea claims is weapon-grade plutonium.  A member of the delegation says the cooling pond there, which formerly held the 8,000 rods, is empty.

February 2004:             A.Q. Khan's confession reopens speculation that a 1998 Pakistani weapon test may have involved North Korea.  American military jets sampled the air after the test and found traces of plutonium, but Pakistan says all its bombs are fueled with HEU.

Second six-nation talks end inconclusively, with North Korea willing to dismantle its nuclear program on terms yet to be reached, provided it can retain a civilian nuclear program.  North Korea continues to deny a uranium enrichment program.

March 2004:                A C.I.A. classified report is said to conclude that North Korea probably received from the A.Q. Khan nuclear network a comprehensive nuclear package, similar to that received by Libya, which included all the equipment and technology it needed to produce uranium-based nuclear weapons.