The White House has released more than 100 pages of emails detailing discussion inside the administration over last year's attacks on a US diplomatic compound in the eastern Libyan city of Benghazi.
The emails were released to the media on Wednesday as President Barack Obama finds himself under increasing pressure from the Republican opposition that his administration covered up details of the assault in which the US ambassador and three other Americans were killed.
A news report last week said memos on the incident were edited to omit a CIA warning of a threat posed by the al-Qaeda.
The emails were the basis for the "talking points" memos that the US Ambassador to the United Nations Susan Rice used when discussing the attacks.
Al Jazeera's Patty Culhane, reporting from Washington, said that the emails seemed to show that the talking points had been adjusted to remove mentions of al-Qaeda.
"This puts tremendous pressure on the Obama administration as they said the talking points were not changed, and it is now clear they were.
"They released the emails to put the controversy behind them. Unusually there were leaks coming out of Congress saying things were in the emails that were not, making the administration look worse and so it felt it had to release them.
"The debate now is whether the adjustment of the talking points had political motivations."
Republicans felt that the Obama administration's refusal to accept that the attacks on the Libyan compound had been linked to a terrorist organisation was born out of political motives.
"Opponents are saying that they don't want to link the attack to al-Qaeda because then the president couldn't say he had kept all Americans safe," our correspondent said.
"The White House is on the defensive right now, and that is why they have taken this incredibly unusual step," our correspondent said.
In the aftermath of the attack on September 11 last year the White House blamed a spontaneous protest, relating to an internet film that was seen to be insulting to Islam, for the violence.