The US Senate Intelligence Committee released a report on the deadly assault on the diplomatic compound in Benghazi, Libya, yesterday, laying blame on the State Department, the intelligence community - even the late ambassador Chris Stevens - for failing to communicate and heed warnings of terrorist activity in the area.
The highly critical report also says the US military was not positioned to aid the Americans in need, though the head of Africa Command had offered military security teams that Stevens - who was killed in the attack - had rejected weeks earlier.
It also said that in the aftermath of the attack - which involved assaults on the compound and an annexe - US analysts confused policymakers by blaming the violence on protesters without enough supporting intelligence.
"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.
There was no comment from the State Department.
The 2012 Benghazi attack have dogged the Obama administration, because then-UN ambassador Susan Rice initially blamed the violence on mob protests over an anti-Islamic film.
Al-Qaeda-linked militant groups were later blamed for the attack on September 11, 2012, in which militants first overran the US mission and soon afterwards fired mortars at the nearby CIA annexe where the Americans were sheltering.
Committee chairman Dianne Feinstein, a Democrat, said she hoped this would put to rest conspiracy theories about the attack.
Its Republican vice-chairman Saxby Chambliss said the report showed that the US government did not do enough to prevent the attack or to protect the diplomatic facility.
"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 on the prior attacks against Westerners in Benghazi , the report states.
It says "tripwires" set to determine when it had become too dangerous to operate in Benghazi were crossed, but ignored.
The report faults the military for being unable to help when needed. "No US military resources in position to intervene in short order in Benghazi to help defend" the US facilities in Benghazi, it said.
The Defence Department had provided a site security team in Tripoli, made up of 16 special operations personnel. The State Department, according to the report, decided not to extend the team's mission in August 2012, one month before the attack.
In the weeks that followed, General Carter Ham, the head of Africa Command, twice asked Stevens to employ the team, and twice he declined, the report said.
White House spokesman Jay Carney said the committee report "largely reaffirms" the earlier findings from an independent panel. He said a number of the committee's security recommendations had already been implemented.
The committee report makes 18 recommendations to improve security at diplomatic and intelligence posts overseas.