As word of Tuesday's terrorist bombing of the U.N. headquarters in Baghdad spread, so too did speculation about whether it was the work of Al Qaeda (search).
There was no immediate claim of responsibility for the attack. But its careful orchestration and very public, Western-world target immediately evoked past strikes by Usama bin Laden's terrorist network.
Dia'a Rashwan, an expert on radical Islam at Egypt's Al-Ahram Center for Political and Strategic Studies (search), said the attack fits "the ideology of Al Qaeda."
"They consider the U.N. one of the international actors who helped the Americans to occupy Palestine and, later, Iraq," Rashwan said.
L. Paul Bremer, the U.S. administrator in Iraq, said it was too soon to speculate on who was behind Tuesday's horrific terrorist bombing — which he characterized as "an attack on the Iraqi people."
"It's hard to know who would have done it," Bremer told Fox News. "It's a bit early to speculate. We need a little more information before we can judge."
The blast, caused by an explosives-laden cement truck that plowed into the area of the U.N.'s headquarters in Baghdad, resembled the Aug. 7 bombing of the Jordanian embassy in the Iraqi capital.
The Baghdad Jordanian Embassy was blown apart by a car bomb in that strike, killing 11 people.
The Jordanian Embassy hit was thought to be the first such terrorist-style bombing in the Iraqi capital since Saddam Hussein's fall in April.
Like the Jordan blast, the U.N. attack was caused by a vehicle bomb that tore through a high-profile target with many civilians inside.
Both strikes mimic attacks blamed on Islamic terrorists elsewhere in the world. They were far more sophisticated than the campaign of guerrilla warfare that has plagued U.S. forces in Iraq. Those have generally been hit-and-run shootings carried out by small bands of soldiers or remote control roadside bombs.
There has been growing concern about terrorist crossing Iraqi borders to boost resistance forces fighting against the U.S.-led Coalition there.
"We are going to have to get a handle on … domestic terror groups inside Iraq," Mark Ginsberg, the former ambassador to Morocco, told Fox News.
Tuesday's violence at the U.N. building followed a series of recent purported warnings from Islamic extremists.
An audiotape that was allegedly made by one such extremist called on Muslims around the world to fight the U.S.-led occupation in Iraq.
The audiotape, broadcasted on Al-Arabiyah TV, featured the voice of Abdur Rahman al-Najdi, a Saudi-born terrorist sought by the U.S.
Also a letter, allegedly from Saddam Hussein's deputy, was read on air by the Al-Arabiya satellite T.V. channel in Dubai that vowed Iraqis would avenge the American killings of Saddam's two sons last month.
During the broadcast, station officials didn't say how they verified the authenticity of the letter or how and when they obtained it.
Al Qaeda has tried to take responsibility for last week's major power outage in the Mid Atlantic region of the U.S., but American officials reportedly laughed out loud when they heard the claim. There is an investigation underway into how the electricity failure happened.
As for Tuesday's tragic U.N. bombing, terrorism and foreign affairs experts told Fox News that terrorists most likely came over from countries such as Syria or Iran and had a hand in the bombing.
The experts agree that Iraqis likely wouldn't carry out such an attack on their own, but they might have helped outside forces in planning it.
Denis Halliday, the former U.N. Secretary General and former coordinator of humanitarian affairs in Iraq, told Fox that a great majority of people in the building were Iraqi citizens working with the U.N.
"There's no history of suicide bombings in Iraq" before the Jordanian embassy attack earlier this month, said Halliday. "I think this is the worst case I've heard of … I've never heard of a bombing of this nature of a U.N. building."
But it will likely take some time to determine if Al Qaeda or some other rebel faction was behind the attack.
Bernard Kerik, the senior U.S. law enforcement official in Baghdad and a former New York City police commissioner, said evidence suggests it was a suicide bombing. But he echoed sentiments that it was too soon to tell for sure if Al Qaeda conducted the hit.
"It's much too early to say," he said. "We don't have that kind of evidence yet."
Fox News' Special Report host Brit Hume, DaySide host Linda Vester and The Associated Press contributed to this report.