Shortly after the Sept. 11 attack on a U.S. consulate in Libya, the Pentagon responded by moving military assets into the region, but some former defense officials say it was too little, too late.
By the morning after the initial violence, Ambassador Chris Stevens and three other Americans were dead, victims of two separate assaults several hours apart.
“For the U.S. military to say they couldn’t move ... one aircraft in eight hours, I say it's time to relieve the people in chain of command," Bing West, an assistant defense secretary under President Reagan, told Fox News.
But U.S. officials argue "strafing the streets of Benghazi" without a clear intelligence picture on the ground could have led to Americans or innocent bystanders being mistakenly hit. Officials also feared an ambush by the attackers.
“It's not as easy as people think,” retired Gen. Jack Keane, former vice chief of the Army staff, said. “It's not as it's displayed in Hollywood. ... They are as concerned about those who they are sending there and having harm come to them as they are about those who are already there under duress.”
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An unarmed U.S. Predator drone already was performing surveillance missions over Libya when the attack on the consulate in Benghazi began at 9:40 p.m. local time. Shortly after the attack, the drone moved into position over the compound.
A quick reaction force from the CIA annex a mile away was sent to help the ambassador and others at the consulate. It eventually returned to the annex with all of the survivors and Sean Smith, a State Department official who had been killed, but not with Ambassador Stevens.
President Obama met with Defense Secretary Leon Panetta and Vice President Biden in the Oval Office at 5 p.m. ET, a little more than an hour after the onset of the attack. The Pentagon began moving military assets:
-- Eight from Special Operations were sent from Tripoli.
-- A "FAST team" (Fleet Anti-terrorism Security team) of Marines from Rota, Spain, were sent to guard the Embassy in Tripoli.
-- A Special Operations force was moved from central Europe to Sigonella Air Base in southern Italy, just 480 miles from Benghazi.
-- F-16s and Apache helicopters remained parked and unused at Aviano Air Base in northern Italy.
-- Two Navy destroyers already in the Mediterranean Sea were moved off the coast of Libya on the day of the attack but were never used.
Asked why the U.S. military did not do more, Defense Secretary Leon Panetta said Thursday the first rule in such a situation is not to deploy troops into harm's way unless there is a clear picture of what is happening.
"And as result of not having that kind of information, the commander who is on the ground ... felt very strongly that we could not put forces at risk in that situation," Panetta said.
Sens. John McCain and Lindsey Graham, both Republicans, complained recently that more was not done to bolster security.
"Despite ample warning signs that the immediate region remained unstable and our people under threat, inadequate preparations were made to respond to what in retrospect seems a likely attack," the senators said in a joint statement released last week.
"We were told reconnaissance aircraft were sent, and that a surveillance drone had been repositioned in response to the attack. But we were both shocked to hear that ... there were no land forces available to support Benghazi."
The senators also criticized the lack of fighter jets available to intervene.
The fighting at the consulate was over within an hour, according to recently leaked State Department emails obtained by Fox News. Officials in Washington reading those cables may have thought at the time that the attack was over, but it is now clear this was a two-pronged assault on two separate locations, spanning more than six hours.
At 4 a.m. local time -- 6 hours and 20 minutes after the initial attack began -- former Navy SEALs Tyrone Woods and Glen Doherty were killed at the CIA annex by a mortar shell. The machine gun they were firing was caked in blood, suggesting they continued fighting after being hit.
"The last two casualties occurred well over six hours after the initial attack," McCain and Graham noted. "It is disappointing to hear that our national command authorities failed to try to reinforce the consulate with timely air assets, and that a consulate located in one of the most dangerous regions in the world was so unsecured."
U.S. officials say a poor intelligence picture on the ground during the attack made a more immediate military intervention imprudent, given the possibility for unintended casualties.
They also say they needed permission from the Libyan government to enter the country's airspace, though West, the former deputy defense secretary, dismissed such an argument.
"If your ambassador has been either killed or captured and is missing ... you don't ask any country for 'mother, may I' before you come across the border to save your own," he said.
But Keane disputed the effectiveness of sending air power into such a volatile, unpredictable scene.
"If you want to bring an airplane over there, what is it really going to do?" he said. "There was probably as many people watching what was taking place -- who are innocent bystanders -- as well as people who are actually attacking the place."
He also warned against jumping to conclusions about U.S. officials' decisions until all the facts are out.
"You don't know what was being communicated," he said. "People from that facility who are tough competent people, they know what that situation was there. You don't know what advice they are providing their chain of command as to what the situation was -- whether they wanted more people to relieve them or whether they were just stalling for time to make that evacuation."
Jennifer Griffin currently serves as a national security correspondent for FOX News Channel . She joined FNC in October 1999 as a Jerusalem-based correspondent. You can follow her on Twitter at @JenGriffinFNC.