The Benghazi report has found no wrongdoing by the Obama administration in responding to the deadly 2012 attack on the US consulate in Libya.
The inquiry by the Republican-run House Intelligence Committee also said there was no intelligence failure and no delay in sending a CIA rescue team.
The Obama administration had been accused of mishandling its response.
Four Americans, including Ambassador Christopher Stevens, died in the raid carried out by Islamist militants.
In a report released on November 21, the committee dismissed a claim that the CIA had not provided adequate security for its own agents near the Benghazi consulate and that the Obama administration had failed to send support.
It said it reached its conclusion based on “thousands of hours of detailed investigation” and interviews with senior American officials and the agents who had been on the ground during the attack on September 11, 2012.
“The CIA ensured sufficient security for CIA activities in Benghazi and, without a requirement to do so, ably and bravely assisted the state department on the night of the attacks,” the report said.
“Appropriate US personnel made reasonable tactical decisions that night, and the committee found no evidence that there was a stand-down order or a denial of available air support.
“The CIA received all military support that was available.”
However, the Benghazi report concluded that the mission had inadequate security and therefore had required CIA assistance.
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Secretary of State Hillary Clinton says she takes responsibility for the security failure at the Benghazi consulate that led to the killing of four Americans in Libya last month.
Hillary Clinton said ensuring the safety of US diplomatic staff overseas was her job, not that of the White House.
Republicans have strongly criticized President Barack Obama over the attack.
And Republican challenger Mitt Romney is likely to raise it again in the second campaign debate with Barack Obama.
It seems Hillary Clinton is trying to draw criticism away from Barack Obama, who needs a strong debate performance if he is to recover his lead in the polls.
In her interviews, Hillary Clinton appeared to acknowledge that she was trying to shield the president.
“What we had to do in the state department was keep focused not on why something happened – that was for the intelligence community to determine – but what was happening and what could happen,” Hillary Clinton said.
“And that’s what I was very much working on, day and night, to try to make sure that we intervened with governments. We did everything we could to keep our people safe, which is my primary responsibility.”
Hillary Clinton said she was focused on tracking down the killers of the US ambassador to Libya and bringing them to justice.
“I don’t think we want to get into any blame game. I think what we want to do is get to the bottom of what happened, figure out what we’re going to do to protect people and prevent it from happening again and then track down whoever did and bring them to justice.”
Last week, a US congressional committee heard US security in Libya was reduced before the attack on the US consulate, even as violence worsened.
Mitt Romney has been making the Benghazi attack the centrepiece of his case against President Obama’s foreign policy, and has accused Vice-President Joe Biden of making misleading statements about the attack.
Mitt Romney said Joe Biden’s statement in the recent vice-presidential debate that the administration was not told about requests for extra security in Libya contradicted the sworn testimony of state department officials.
A congressional panel has already heard there had been repeated requests to the state department for beefed-up security at the diplomatic compound.
In the days after the attack, Barack Obama’s ambassador to the United Nations, Susan Rice, described it as a “spontaneous” assault that arose out of a protest against a US-made amateur video which mocks Islam.
But US officials have since said the government had never concluded the attack was motivated by the film.
Barack Obama and Mitt Romney are preparing to face off in their second debate later on Tuesday, at Hofstra University in Hempstead, New York.
Mitt Romney was widely acknowledged as having the upper hand in the first debate, which was reflected in the opinion polls, with many showing for the first time in the campaign Mitt Romney in the lead.
Ambassador Christopher Stevens died of smoke inhalation when he was trapped alone in the burning consulate building on 11 September. Three other officials were killed, and three wounded.
Earlier this week, the father of Ambassador Christopher Stevens said it would be “abhorrent” to turn his son’s death into a campaign issue.
“Our position is it would be a real shame if this were politicized,” Jan Stevens said.