(CNN) -- Following is a summary of the long-running standoff between Iraq and the United Nations over the U.N. demand that Iraq eliminate its weapons of mass destruction.

January 13, 1998: Iraq prevents U.N. arms inspectors led by American Scott Ritter from working. Iraq says Ritter is a spy, a charge the American rejects.

January 17: Saddam Hussein threatens to halt inspections.

February 6: A further 2,200 U.S. Marines head for Gulf.

February 12: Iraq will not accept demand for unfettered U.N. access to all presidential palaces.

February 18: U.N. Secretary-General Kofi Annan sees "reasonable chance" of averting military action; United States says odds are poor.

February 19: First U.S. army reinforcements arrive in Kuwait.

February 20: Annan arrives in Baghdad, saying he has a "sacred duty" to try to defuse the crisis. Security Council more than doubles the amount of oil Iraq is allowed to sell under "oil-for-food" program to buy food and medicines.

February 21: Clinton and senior advisers refine plans for airstrikes if Baghdad refuses unrestricted access for inspectors. Washington urges all its citizens to leave Iraq.

February 22: Annan holds three-hour meeting with Saddam, and the U.N. chief's spokesman later announces a deal on inspections.

February 23: Annan says there are "no time limits or deadlines" in the pact. The agreement provides for a "special group," comprising U.N. weapons experts and senior diplomats, to carry out inspections of the eight presidential sites.

March 2: Security Council members agree informally on a resolution warning Iraq of "severest consequences" if it again bars U.N. weapons inspectors from suspected sites.

March 3: U.S. Ambassador Bill Richardson says the new resolution gives Washington enough authority to use force against Baghdad if it again blocks inspectors.

March 5: Ritter returns to Baghdad.

March 12: U.N. technical team arrives in Baghdad to assess the repairs needed to increase Iraq's oil export capacity.

March 23: Chief U.N. weapons inspector Richard Butler holds his first talks in Baghdad since the inspectors' row.

March 26: U.N. arms monitors begin mission to inspect presidential site for first time in seven years' work.

April 9: U.N. report says Iraq still failing to provide a full account of its biological warfare program.

April 15: U.N. report says Iraq appears to be setting limits on future access to palaces and has tried to circumvent arms inspectors by appealing to diplomats and Annan.

April 28: Iraqi foreign minister denies that an agreement between Baghdad and the U.N. secretary-general permitted unlimited inspections of Iraqi presidential palaces.

May 1: Iraq warns U.N. Security Council that prolonging sanctions will lead to "grave consequences."

May 25: Iraq says it will hold up oil sales unless the United Nations approves a new oil-for-food program due to start on June 4.

May 30: Annan approves Iraqi plan on how it will distribute food and medicines.

June 8: Butler says Security Council members may be ready to accept less than 100 percent verification that Iraq has destroyed its weapons of mass destruction.

June 14: Iraq and U.N. weapons inspectors agree on a two-month schedule of action for outstanding disarmament work.

June 17: Baghdad will force a "last crisis" if sanctions are still in place at the end of this year, Iraqi Ambassador to the United Nations Nizar Hamdoon says.

June 20: The U.N. Security Council authorizes $300 million in equipment to upgrade Iraq's deteriorating oil industry.

June 23: U.S. officials said tests showed Iraq put VX nerve gas into missile warheads before the 1991 Gulf War, prompting Clinton to say sanctions must stay in place. Iraq says U.S. army laboratory report cannot be accurate.

June 30: U.S. F-16 warplane fires a missile at Iraqi air defenses after an Iraqi anti-aircraft battery locks its radar onto a British plane patrolling a no-fly-zone, U.S. military officials say. Iraq denies targeting allied planes.

July 23: Butler complains to the Security Council that Iraq is refusing to hand over documents on munitions used in the 1980-1988 war with Iran.

July 27: The International Atomic Energy Agency says it has no evidence Iraq has any nuclear arms or related materials but that information on past programs is incomplete.

July 29: Russia proposes a Security Council resolution saying Iraq has complied with demands to destroy its nuclear arms facilities, splitting the 15-member body.

July 31: Iraq accuses an American member of a United Nations arms team of spying during an inspection.

August 3: U.S. House of Representatives votes to find Iraq in "material and unacceptable breach" of its international obligations, specifically its violations of no-fly zones in southern Iraq and its concealment of weapons programs.

August 4: Butler leaves Baghdad after talks with Iraqi officials break down. He says Iraq has rejected his proposal to extend his team's work.

August 9: The U.N. Special Commission suspends inspections of new sites in Iraq after Baghdad's August 5 decision to halt cooperation with the United Nations.

August 26: Ritter resigns his U.N. post.

September 9: In a move to punish Iraq for defying inspectors, the Security Council suspends its periodic reviews of sanctions.

October 31: Iraq suspends all cooperation with U.N. arms inspectors and monitors.

November 5: The U.N. Security Council votes unanimously to condemn Iraq and demands that it immediately resume cooperation with weapons inspectors.

November 7: The United Nations begins withdrawing its arms inspectors from Baghdad.

Reuters contributed to this report.