And some of the key ones concern the United Nations.

Has its failure to halt the US's quest for war in Iraq effectively made the world body irrelevant? Is international law now the weakest link in the unfolding crisis in occupied Iraq? Who defines the UN's course of action, its power and scope?

The following timeline is a review of some of the momentous events that shaped the UN's role in the invasion, occupation and reconstruction of Iraq.

12 September 2002: Bush called on the UN to act boldly and quickly to disarm Iraq, warning that the international body's reputation was at stake and that yielding to Iraqi President Saddam Hussein's government could render the UN "irrelevant".

8 November 2002: The UN Security Council unanimously adopted resolution 1441, drafted by the US and UK. The resolution affirmed that Iraq had been and remained in "material breach" of its obligations under previous resolutions, and demanded Iraq to cooperate immediately, unconditionally and actively with UN inspectors.

The resolution declared that only weapons inspectors - not UN member states - had the authority to report Iraqi violations. The resolution, however, was subject to interpretation. The US contested that 1441 gave it the authority to launch a war against Iraq, while other members of the council insisted the resolution did not authorise the automatic use of force.

5 February 2003: In an address to the Security Council, US Secretary of State Colin Powell exhibited satellite photos demonstrating that: "Saddam Hussein and his regime have made no effort to disarm, as required by the international community." Powell argued that his demonstration was "based on solid intelligence," hence concluding that Iraq was in "material breach" of UNSC Resolution 1441.

14 February 2003: UN weapons inspector Dr Hans Blix and International Atomic Energy Agency (IAEA) Director-General Muhammad al-Baradai briefed the UN Security Council on Iraq's weapons programme. Their briefings were followed by statements by French Foreign Minister Dominique de Villepin and German Foreign Minister Joschka Fischer who reiterated their countries' opposition to war.

22 February 2003: In a Paris conference, 52 African countries, including three Security Council members, joined the anti-war camp by declaring their support of France's opposition to possible US military action against Iraq.

Chirac and Schroeder, along with
Russia's Putin, opposed the war

24 February 2003: France, Russia and Germany proposed an alternative to war, a detailed plan for Iraq’s disarmament based on a rigorous and intensified weapons inspection programme.

5 March 2003: France, Russia and Germany declared their opposition to a US-UK draft resolution on Iraq. "We will not let a proposed resolution pass that would authorise the use of force," a joint statement read. "Russia and France, as permanent members of the Security Council, will assume all their responsibilities on this point."

6 March 2003: Whereas China stated its opposition to a new resolution on Iraq, Bush stressed that the US should prepare for war, whether or not a UN authorisation was obtained.

7 March 2003: The UK introduced an amendment to a US-UK-Spanish resolution that would pave the way for war on Iraq. Supported by Washington, the draft resolution declared: "Iraq will have failed to take the final opportunity afforded by resolution 1441 unless, on or before 17 March 2003, the council concludes that Iraq has demonstrated full, unconditional, immediate and active cooperation." France immediately rejected the draft, declaring through its foreign minister, de Villepin, "We cannot accept an ultimatum as long as inspectors are reporting cooperation."

11 March 2003: In a joint press conference with Prime Minister Jan Peter Balkenende of the Netherlands at The Hague, UN Secretary General Kofi Annan said that if there was no UN authorisation for military action, "the legitimacy and support of any such action will be seriously impaired".

13 March 2003: Britain introduced a new proposal setting out six ways for Saddam Hussein to prove his commitment to disarmament and avoid an invasion. The proposal was met by sharp opposition from some UN member states.

16 March 2003: Bush, British Prime Minister Tony Blair and Spanish Prime Minister Jose Maria Aznar met in the Portuguese Azores Islands in the eastern Atlantic. White House spokesman Ari Fleischer described the meeting as "an effort to pursue every last bit of diplomacy".

17 March 2003: A draft resolution by the US, Britain and Spain, which declared: "Iraq will have failed to take the final opportunity afforded by resolution 1441 unless, on or before 17 March 2003, the council concludes that Iraq has demonstrated full, unconditional, immediate and active cooperation," was withdrawn due to lack of support at the Security Council.

17 March 2003: Annan told journalists at the Security Council, "If [military] action is to take place without the support of the council, its legitimacy will be questioned and the support for it will be diminished."

US President George Bush issued
an ultimatum in March 2003

18 March 2003: Bush brought the world to the edge of war by issuing an ultimatum for Saddam and his sons to leave Iraq within 48 hours. "Their refusal to do so will result in military conflict, commenced at a time of our choosing. For their own safety, all foreign nationals, including journalists and inspectors should leave Iraq immediately,” Bush warned.

18 March 2003: Iraq rejected the US ultimatum and the UN was obliged to pull its arms inspector out of the country.

20 March 2003: US-British war on Iraq began with the first US attack on Baghdad with Tomahawk missiles and precision-guided bombs aimed at President Saddam Hussein and senior government officials.

28 March 2003: The Security Council unanimously approved adjustments to the oil-for-food programme. The resolution granted Kofi Annan more authority to administer the programme and provide humanitarian aid to Iraqi civilians.

18 April 2003: Bush urged the UN to lift economic sanctions imposed on Iraq. But Russia insisted that sanctions would not be lifted until it was certain that Iraq did not possess banned weapons.

9 May 2003: Washington, backed by London and Madrid, introduced a draft resolution seeking an immediate lift of sanctions and the phasing out of the oil-for-food programme. The resolution would give the US and Britain control over Iraq’s political development and financial resources for 12 months, relegating the UN to an advisory role.

15 May 2003: In an effort to win the support of France, Russia, China and Germany, the US and the UK amended their draft resolution to give what they called an "enhanced" role to the UN. The draft failed to respond to many major concerns, and most changes appeared insubstantial and largely cosmetic.

22 May 2003: The Security Council adopted resolution 1483, recognising the US and Britain's occupation of Iraq and lifting economic sanctions. The resolution, adopted 14-0 with Syria absent, assigned the UN only a limited role in a transition to democratic government.

17 July 2003: Annan outlined his overall approach for a UN presence in Iraq in his first report to the council. The report called for a clear timetable for the restoration of sovereignty with specific steps for ending the US military occupation.

UN special envoy Sergio Vieira de
Mello died in an attack in 2003

14 August 2003: The Security Council adopted resolution 1500, welcoming the establishment of the Iraqi Governing Council (IGC). It also established the UN assistance mission for Iraq as proposed by the Secretary General in his July report, fulfilling his mandate under resolution 1483.

19 August 2003: The UN headquarters in Baghdad was attacked, killing top UN envoy Sergio Vieira De Mello and 21 others. The attack forced the UN to pull its non-Iraqi staff out of the country because of the deteriorating security situation.

4 September 2003: In a draft resolution presented by the US, Washington asked the UN to back the deployment of international troops and the sharing of the financial burden of rebuilding Iraq. The draft however did not stipulate that Washington was ready to share the responsibility of administering Iraq with the UN.

10 September 2003: France and Germany presented their amendments to the US draft resolution, giving the UN a primary role in the development of new political institutions in Iraq. The modifications also asked the "coalition" forces to accelerate the restoration of Iraqi sovereignty and called for full transparency over international reconstruction funds.

23 September 2003: Addressing the UN General Assembly, almost a year after threatening to render the UN "irrelevant", Bush said: "As an original signer of the UN charter, the United States is committed to the United Nations."

1 October 2003: The US offered a new draft resolution that took into account some concerns of Security Council members, but without addressing central issues about the UN role and the end of the occupation.

13 October 2003: Co-sponsored by the UK and Spain, the US introduced a third draft resolution, giving the IGC until 15 December 2003 to submit a timetable for drafting a constitution and holding elections. The text, however, did not give a sizeable role or power to the UN.

16 October 2003: The Security Council unanimously adopted resolution 1511 after the US accepted some proposed amendments from France, Russia and Germany.

15 November 2003: The US and the IGC signed an agreement aimed at forming regional caucuses that would select an Iraqi national assembly by the end of May 2004, which would in turn select a transitional government by 30 June.

Captured in late 2003, Saddam
was declared a prisoner of war

13 December 2003: Saddam was captured by occupation forces in Iraq.

16 December, 2003: Annan asked Security Council for greater clarity on UN role in Iraq.

19 January, 2004: In a press conference following talks in New York with members of the IGC and representatives of the US-led Coalition Provisional Authority (CPA), Annan said he was considering a request by the parties to send an advisory team to Iraq to examine the feasibility of elections before the end of June as well as possible alternatives.

19 January 2004: Senior officials from the IGC and CPA welcomed the UN involvement in the transitional period ahead.

3 February 2004: Following a meeting with Annan in Washington, Bush said, "The United Nations does have a vital role there (in Iraq), and I look forward to working with the Secretary General to achieve that."

7 February 2004: Annan expressed hope the UN effort would help resolve the impasse over the transitional political process leading to the establishment of a provisional government in Iraq following the arrival of a United Nations fact-finding team to Baghdad.

13 February 2004: Following a meeting in Baghdad with the IGC, Lakhdar Ibrahimi, Annan's special adviser and head of the UN team assessing the prospects for early elections in Iraq, said the timing of the elections should not be held prisoner to any deadline.

24 February 2004: US and British officials welcomed the growing UN involvement in Iraq's political future. Briefing the Security Council on the latest developments in Iraq, the US Ambassador to the UN welcomed Annan’s report on a fact-finding mission analysing the feasibility of holding elections in Iraq.