The attacks that killed four Americans in Libya including Ambassador Christopher Stephens could have been prevented by rectifying "known security shortfalls" at the US missions in Benghazi, a Senate report concluded Wednesday.
Senate Intelligence Committee investigators conducted dozens of hearings and interviews with survivors of the double attack targeting the US diplomatic facility and the nearby CIA annex in the eastern city of Benghazi on September 11, 2012.
The deadly attack triggered a political scandal in the United States, with Republican lawmakers accusing President Barack Obama's administration of trying to conceal the nature of the attacks and blaming them on militants motivated by an anti-Islamic film posted online.
The glaring failures that saw attackers breach the security cordon also shocked Republicans, who held a year-long string of contentious congressional hearings featuring scores of administration officials.
The report, which issued several findings regarding the assaults, said the State Department failed to heed warnings to boost security at the sites despite the rapidly deteriorating security environment in Libya.
And it blamed intelligence agencies for not notifying US military officials in the US Africa command that a CIA annex even existed near the Benghazi diplomatic mission.
"The committee found the attacks were preventable, based on extensive intelligence reporting on the terrorist activity in Libya — to include prior threats and attacks against Western targets — and given the known security shortfalls at the US mission," the panel said in a statement.
"The State Department should have increased its security posture more significantly in Benghazi based on the deteriorating security situation on the ground and IC (intelligence community) threat reporting."
The 85-page report also attempts to clarify the confusion surrounding the Obama administration's initial statements about the attacks, when they "inaccurately" referred to a protest at the US mission prior to the assault "without sufficient intelligence or eyewitness statements to corroborate that assertion."
Intelligence leaders then took "too long to correct these erroneous reports," adding to public confusion about what happened.
The report also makes the grim assessment that the FBI probe into the attacks has been stymied in Benghazi, where "as many as 15 individuals supporting the investigation or otherwise helpful to the United States have been killed" since the attacks.
The report is bound to fuel controversy over the responsibility of the State Department, headed by then-secretary of state Hillary Clinton, and more broadly the Obama administration, which has identified several individuals responsible for the attacks but has failed to bring them to justice.