In a briefing to Capitol Hill staffers delivered the day after the deadly Sept. 11 attack in Benghazi, a top aide to Secretary of State Hillary Clinton said the killings appeared to be the result of a terrorist attack.

Under Secretary of State for Management Patrick F. Kennedy -- who exercises responsibility for all department personnel, facilities, and operations, and who is one of the department's most respected civil servants, having served in his position under both the George W. Bush and Obama administrations -- delivered the assessment in an unclassified, half-hour conference call with staff aides to House and Senate lawmakers from relevant committees, and leadership offices, on the evening of Sept. 12. Capitol Hill sources described the call to Fox News.

That a State Department official of Kennedy's rank -- one with direct oversight of the installations and people targeted in Benghazi -- reached such a conclusion so swiftly stands in stark contrast to the opposing narrative pressed at that time, and for several days afterward, by other top officials at State, the White House, and the intelligence agencies.

Four days after Kennedy's conference call, for example, U.S. Ambassador to the United Nations Susan Rice appeared on five Sunday morning talk shows to insist that the attacks were neither coordinated nor premeditated, but were rather the result of a spontaneous mob action, inspired by an anti-Muslim video on the Internet, that spun out of control.

Rice has since told lawmakers that her comments reflected "the intelligence community's best, current assessment as of the date of my television appearances," and a spokesman to the Director of National Intelligence, James R. Clapper, has said in a statement that the intelligence community "revised our initial assessment to ... (conclude) that it was a deliberate and organized terrorist attack carried out by extremists."

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The State Department suggests Kennedy did not go as far as to draw conclusions about the origins of the attack in his Capitol Hill briefing.

"Under Secretary Kennedy was asked about the nature of the assault, and he described its ferocity and lethality -- not what led to it," State Department spokesman Mark Toner told Fox News.

According to participants on the Kennedy call, the under secretary noted he is not a "security expert," but then focused on the presence of light and heavy weapons outside the U.S. consulate and annex in Benghazi where U.S. Ambassador to Libya Chris Stevens and three other Americans had been killed the night before.

"He made clear that this was a sophisticated attack," said one Hill staff aide with a security clearance. "He indicated this was fairly complex, and not, like, a protest that got out of hand. ... These were not the kind of weapons you tote around."

In subsequent days, Kennedy delivered an in-person, classified briefing to a group composed of many of the same congressional staff aides who had participated on the Sept. 12 conference call.

Fox News and other news organizations have previously reported that earlier on Sept. 12 -- within 24 hours of learning about the murders -- the Obama administration made a secret determination that Benghazi was indeed a terrorist attack. Doing so enabled them, under the terms of a 2001 anti-terrorism statute, to move men, money and materiel around more freely, and position these assets to meet the threats in Libya and other parts of the Mideast that had recently seen attacks on U.S. installations. Kennedy's assessment accorded with that determination.

This leaves unexplained how Rice, ostensibly armed with the intelligence community's best assessment, could have offered such a starkly different account in her Sunday show appearances. As late as Sept. 17, Fox News reported last week, high-level U.S. intelligence officials obtained from outside security contractors assessments of the mortar damage done at the U.S. annex in Benghazi. Sources told Fox News these officials then used the contractors' mortar damage assessments -- which indicated the presence of at least two highly skilled mortar teams using GPS devices -- to rebut Rice's claims internally.

The next day, on Sept. 19, Matthew Olsen, director of the National Counterterrorism Center, testified publicly that the attacks were an act of terrorism -- which effectively ended the internal disputes roiling the Obama administration and the intelligence community.