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When homicide bombers destroyed the U.N. headquarters in Baghdad — killing 22 people in one of the deadliest days since the fall of Saddam Hussein — it left the global organization's reputation as a guarantor of peace in shambles.

The Aug. 19 blast and its aftermath point to a threat the United Nations (search) didn't really contemplate when it was created nearly 60 years ago — the insidious threat of terrorism.

Instead of defying the terrorists after the Baghdad explosion, Secretary General Kofi Annan (search) ordered personnel out of Iraq and opted to run the Iraq operation from Jordan and the Mediterranean island of Cyprus.

"We need to take measures to protect ourselves," Annan told Fox News in an exclusive interview. "We don't want to be in bunkers, we can't, our work is people, we need to be able to have access to them and they have to have access to us."

Nonetheless, according to its critics, the United Nations cut and ran.

"If the U.N. sets this pattern of when things get dangerous, they are going to leave a country ... It bodes very poorly," said Richard Williamson (search), part of the U.S. delegation to the United Nations. "It encourages further disruption and also will gradually have the U.N. recede as an important player."

In fact, the United Nation's very reason for existence — maintaining collective world security — has come into question.

The U.S.-led war in Iraq and the U.N. Security Council's failure to enforce 17 resolutions against Saddam Hussein have raised the question of whether the United Nations can ever do anything significant about the major threats of our time.

The failures have become a tragic refrain.

— Thousands of Bosnian Muslims were slaughtered in the U.N. safe haven of Srebrenica (search) around 1995.

— In Rwanda (search), 800,000 Tutsis and moderate Hutus were hacked to death in 1994 while a divided Security Council was unable to agree to reinforce a U.N. authorized peace mission.

Yet the United Nations also has had successes:

In war-ravaged East Timor (search), a mostly Australian U.N. force ended bloodshed and led the nation to independence in 2002.

Almost everybody, however, agrees that the United Nations needs an overhaul that recognizes it is not the universal answer to global problems that some want it to be.

"In terms of the U.N. being a bulwark of peace, which is what its founders have imagined, that has proven to be a pipe dream," said Joshua Muravchik (search), an analyst with the American Enterprise Institute.

John Dauth (search), the Australian ambassador to the United Nations, said there was no formula for the future. "But we certainly think that the organization needs to be more focused, more contemporary, more representative," he said.

Annan has appointed a high-level panel to study the world body's role in facing global threats. It will present its recommendations in a year.

Part of the panel's challenge will be to decide how the organization should respond to terrorism and how it should deal with members who are linked to terrorist acts.

Terrorists are often backed by shadowy organizations that sometimes get secret support from governments — governments that are also members of the United Nations.

In fact, when the U.N, headquarters was bombed in Baghdad, the Security Council presidency was held by Syria, a nation on the U.S. State Department's list of terrorist sponsors.

More than 30 years ago, the United Nations couldn't agree whether the massacre of Israeli athletes at the 1972 Munich Olympics was a terrorist act. That logjam continues today, even though the United Nations has produced a dozen treaties outlining specific criminal acts associated with terrorism such as airline hijacking and money-laundering.

"The (U.N. Security) Council has been very active and come up with a very strong resolution ... to ensure that governments cooperate, they do not harbor terrorists, they do not allow them to hold their finances in their countries, and no logistical support is given to them," Annan told Fox News.

Yet the General Assembly's legal committee has been struggling for 10 years to produce a draft treaty on terrorism.

"Kofi was interested in having more of a U.N. response to terrorism, but ... the Organization of Islamic States vetoed it. They said they would not go along with any resolution against terrorism unless it said terrorism for bad causes is bad, but terrorism for good causes is good," Muravchik said.

Some think a divided Security Council could lead the United States and its allies to ratify their own conventions on terrorism and then encourage or pressure other nations to join in. In that case, it could be up to the United Nations to catch up or be left behind.