Last Updated 3:40 p.m. ET
(CBS News) The closer we get to the election, the harder Republicans in Congress are pushing for answers to a big question: What really happened in the attack on the U.S. Consulate in Benghazi, Libya last month that killed the U.S. Ambassador Christopher Stevens and three other Americans?
Some lawmakers are asking why U.S. military help from outside Libya didn't arrive as terrorists battered more than 30 Americans over the course of more than seven hours. The assault was launched by an armed mob of dozens that torched buildings and used rocket propelled grenades, mortars and AK-47 rifles.
CBS News has been told that, hours after the attack began, an unmanned Predator drone was sent over the U.S. mission in Benghazi, and that the drone and other reconnaissance aircraft apparently observed the final hours of the protracted battle.
The State Department, White House and Pentagon declined to say what military options were available. A White House official told CBS News that, at the start of the attack, Chairman of the Joint Chiefs Martin Dempsey and Defense Secretary Leon Panetta "looked at available options, and the ones we exercised had our military forces arrive in less than 24 hours, well ahead of timelines laid out in established policies."
But it was too late to help the Americans in Benghazi. The ambassador and three others were dead.
A White House official told CBS News that a "small group of reinforcements" was sent from Tripoli to Benghazi, but declined to say how many or what time they arrived.
Retired CIA officer Gary Berntsen believes help could have come much sooner. He commanded CIA counter-terrorism missions targeting Osama bin Laden and led the team that responded after bombings of the U.S. Embassy in East Africa.
"You find a way to make this happen," Berntsen says. "There isn't a plan for every single engagement. Sometimes you have to be able to make adjustments. They made zero adjustments in this. They stood and they watched and our people died."
The Pentagon says it did move a team of special operators from central Europe to the large Naval Air Station in Sigonella, Italy, but gave no other details. Sigonella is just an hour's flight from Libya. Other nearby bases include Aviano and Souda Bay. Military sources tell CBS News that resources at the three bases include fighter jets and Specter AC-130 gunships, which the sources say can be extremely effective in flying in and buzzing a crowd to disperse it.
Rick Nelson, a senior fellow at the Center for Strategic and International Studies and a former Navy pilot who worked in counter-terrorism, says such missions can be very risky. "A lot can go well, right, as we saw with the bin Laden raid. It was a very successful event," he says. "But also, when there are high risk activities like this. a lot can go wrong, as we saw with the Iranian hostage rescue decades ago."
Add to the controversy the fact that the last two Americans didn't die until more than six hours into the attack, and the question of U.S. military help becomes very important.
Sending the military into another country can be a sensitive and delicate decision. CBS News has been told Secretary of State Hillary Clinton did seek clearances from Libya to fly in their airspace, but the administration won't say anything further about what was said or decided on that front.
To see Sharyl Attkisson's report, click on the video in the player above.