The bombing of the Iraqi headquarters of the United Nations has been compared in immensity to the loss of Dag Hammarskjöld in 1961, writes Colum Lynch
The bombing of the UN headquarters in Baghdad on Tuesday represented the most brazen assault against a civilian UN target since the organisation was founded at the end of the second World War.
It ended decades of relative immunity for UN personnel from Middle East terrorism.
The death of 24 UN officials, including the organisation's top representative in Iraq, Mr Sergio Vieira de Mello, raised concern among some officials that the world body's role in Iraq may increase its exposure to extremist attacks in the region.
Traditionally viewed as an advocate of many popular causes in the Arab world, particularly the Palestinians' pursuit of self-determination, the United Nations has been largely spared by the region's militants. But with the organisation embracing the US-led war on terrorism and promoting a US-appointed Iraqi Governing Council in Iraq, it has struggled to maintain its independence.
"For the United Nations, this tragedy is up there with the death of (then secretary general) Dag Hammarskjöld" - the Swedish diplomat killed in an air crash in the Congo in 1961 - a senior UN official said.
"I would think that [the perpetrators\] are hoping their action would be seen as justified by a section of the local \, who believe the United Nations has sold out and is part of the US-Israeli world order. We do our best to rebut it, but it's not easy."
The emotional impact of the explosion could be felt at UN headquarters in New York, where diplomats, journalists and UN staff members broke into tears when they learned that friends or loved ones had perished in the rubble.
Mr Salim Lone, a UN spokesman in Baghdad whose interview on CNN was broadcast on television screens throughout the building, summed up the staff's emotions when he said: "These wonderful people I know are lying dead here."
As the United Nations headquarters lowered its flag to half-mast, the Secretary General Mr Kofi Annan cancelled a holiday in Sweden to return to New York. Mr Annan vowed that the United Nations will continue its efforts to restore peace and sovereignty to Iraq.
"I grieve deeply for those who have died, and express my heartfelt sympathy to their loved ones," he said.
Syria, which currently holds the presidency of the Security Council and which has resisted UN pressure to grant greater legitimacy to the Iraqi Governing Council, said the council will not be deterred by the bombing.
Mr Fred Eckhard, Mr Annan's spokesman said: "I think you have two strong political signals - one from the council, one from the Secretary General himself - that we are going to stay the course. We don't intend to have our work deterred by this attack."
UN officials said Mr Vieira de Mello is the most senior UN official to be killed in the Middle East since a top mediator, Folke Bernadotte, was assassinated by an Israeli militant group in 1949.
"This is the first time that an attack of such significance [has taken\] place against an installation of the United Nations," Mexico's ambassador to the United Nations, Mr Adolfo Aguilar Zinser, said. "In prior occasions, \ installations have been attacked in the process of a conflict. But this is a major terrorist attack against the United Nations."
The bombing came as the United Nations is playing an increasingly important role in legitimising the Iraqi Governing Council. Last month, Mr Vieira de Mello delivered an impassioned plea to the Security Council to give its blessing to the Iraqi body as a first step in the country's advance towards self-rule.
UN officials said they had no idea who carried out the attack.
"To my knowledge, we have not received any threats that we could link this attack to, nor anyone phoning in to claim responsibility," Mr Eckhard said.
Some speculated that the attack was carried out by supporters of the former Iraqi government or of al-Qaeda, whose leader, Osama bin Laden, has led a campaign to vilify the United Nations by portraying it as an agent of the United States.
"The United Nations is nothing but a tool of crime," bin Laden said in a video-taped message in November.
Mr Richard Holbrooke, a former US ambassador to the United Nations, said the attack was likely aimed at undermining the US effort to restore democracy in Iraq.
"An attack on the United Nations is an attack on the United States," Mr Holbrooke said.
"The UN is a soft target, just like oil pipelines and water mains. They got very lucky, and we got very unlucky because we lost some of the best people in the international system today."