By ERIC SCHMITT and MICHAEL R. GORDON
c. 2012 New York Times News Service
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The investigation into the attack on the diplomatic mission and the C.I.A. annex in Benghazi that resulted in the deaths of Ambassador J. Christopher Stevens and three other Americans also faulted State Department officials in Washington for ignoring requests from the American Embassy in Tripoli for more guards for the mission and for failing to make sufficient safety upgrades.
The panel also said American intelligence officials had relied too much on specific warnings of imminent attacks, which they did not have in the case of Benghazi, rather than basing assessments more broadly on a deteriorating security environment.
By this spring, Benghazi, a hotbed of militant activity in eastern Libya, had experienced a string of assassinations, an attack on a British envoy's motorcade and the explosion of a bomb outside the American Mission.
Finally, the report blamed two major State Department bureaus — Diplomatic Security and Near Eastern Affairs — for failing to coordinate and plan adequate security.
The panel also determined that a number of officials had shown poor leadership, but they were not identified in the unclassified version of the report that was released.
“Systemic failures and leadership and management deficiencies at senior levels within two bureaus,” the report said, resulted in security “that was inadequate for Benghazi and grossly inadequate to deal with the attack that took place.”
The attack in Benghazi and the Obama administration's explanation of what happened and who was responsible became politically charged issues in the waning weeks of the presidential campaign, and Republicans have continued to demand explanations since then.
Susan E. Rice, the United States ambassador to the United Nations, took herself out of consideration for secretary of state after Republican criticism of comments she made in the aftermath of the lethal attack threatened to become a divisive political battle.
The report affirmed there were no protests of an anti-Islamic video before the attack, contrary to what Ms. Rice had said on several Sunday talk shows days after the attack.
While the report focused on the specific attack in Benghazi, the episode cast into broader relief the larger question of how American diplomats and intelligence officers operate in increasingly unstable environments, like those in the Arab Spring countries across North Africa and the Middle East, without increased security.
In response to the panel's findings, Secretary of State Hillary Rodham Clinton said in a letter to Congress that she was accepting all 29 of the panel's recommendations, five of which are classified.
“To fully honor those we lost, we must better protect those still serving to advance our nation's vital interests and values overseas,” Mrs. Clinton said in the letter. She is already taking specific steps to correct the problems, according to officials.
They say the State Department is asking permission from Congress to transfer more than $1.3 billion from contingency funds that had been allocated for spending in Iraq.
This includes $553 million for hundreds of additional Marine security guards worldwide; $130 million for diplomatic security personnel; and $691 million for improving security at installations abroad.
Noting that the Libyan militias in Benghazi proved unreliable, the report recommended that in the future the United States must be “self-reliant and enterprising.”
In recent weeks, teams of State Department and Pentagon security specialists have been sent to 19 “high threat” diplomatic posts around the world to conduct assessments.
The State Department last month for the first time also appointed a senior official — a deputy assistant secretary of state — to ensure that embassies and consulates in dangerous places get sufficient attention.
To that end, the department is revamping deployment procedures to increase the number of experienced and well- trained personnel serving in those posts, and to reduce the high turnover rate that the panel identified as a problem.
The panel, called an accountability review board, is led by Thomas R. Pickering, a retired diplomat, and presented its report to the State Department on Monday.
Its four other members include Mike Mullen, the retired admiral who was chairman of the Joint Chiefs of Staff, and is authorized by a 1986 law intended to strengthen security at United States diplomatic missions.
The State Department sent a lengthy classified version of the report to Congress on Tuesday.
Pickering and Admiral Mullen are scheduled to meet with members of the Senate Foreign Relations Committee and the House Foreign Affairs Committee in closed session on Wednesday.
On Thursday, William J. Burns and Thomas R. Nides, both deputy secretaries of state, will testify in a public session before both panels.
Mrs. Clinton, recovering from a concussion she suffered last week after fainting from a stomach flu, is at home this week.
The review principally addressed seven main categories of problems, mostly related to the State Department. These included the ineffective security provided by the host nation; staffing shortfalls, including high turnover among American diplomatic security personnel; faulty fire-safety and security equipment, including surveillance cameras; and poor performance by specific officials.
“The short-term, transitory nature of special mission Benghazi's staffing, with talented and committed, but relatively inexperienced, American personnel often on temporary assignments of 40 days or less, resulted in diminished institutional knowledge, continuity, and mission capacity,” said the report, which recommended extending those tours to at least one year.
Ambassador Stevens had e-mailed his superiors in Washington in August alerting them to “a security vacuum” in the city.
But the report found that in planning his trip there in September, he did not foresee that the compound could come under such a sustained attack, which included mortars and rocket-propelled grenades, despite the worsening security situation.
“His status as the leading U.S. government advocate on Libya policy, and his expertise on Benghazi in particular, caused Washington to give unusual deference to his judgments,” it said.
Stevens was making his first visit to Benghazi in 10 months.
But his plans for taking only two American security agents “were not shared thoroughly with the embassy's country team, who were not fully aware of the planned movements off the compound,” the report determined.
Officials said the review did not address the limitation in the capabilities of the American military command responsible for a large swath of countries swept up in the Arab Spring.
On the night of the attack, the Pentagon was able to divert an unarmed Predator drone operating 90 miles away to Benghazi, and the C.I.A. later used it to help plan an escape route for the surviving Americans.
But other military forces were too far away or could not be mobilized in time.