THE FIRST OFFICIAL report on the Sept. 11 attack on the U.S. mission in Benghazi, Libya, appropriately focuses on the failures of security and intelligence that allowed the compound to be overrun, leading to the death of Ambassador J. Christopher Stevens and three other Americans. According to the Accountability Review Board established by the State Department, “systemic failures of leadership and management deficiencies at senior levels within two bureaus of the State Department resulted in a . . . security posture that was inadequate for Benghazi and grossly inadequate to deal with the attack that took place.”

Intelligence agencies failed to connect the dots between the deteriorating security situation in Benghazi, the proliferation of “violence prone and little-understood militias” and a “more specific and timely analysis of the threat to U.S. government facilities,” the board found. Bureaucrats at State, meanwhile, resisted and slow-rolled repeated requests for additional security officers at the mission — which, because it was not officially identified as a consulate, was exempted from laws mandating higher security standards.

The report makes an important start toward establishing accountability for Benghazi and preventing a repeat at other missions. Three senior officials at State, including the assistant secretary for diplomatic security and a deputy, were reported to have resigned under pressure Wednesday. The board offered two dozen recommendations, which Secretary of State Hillary Rodham Clinton said she accepted and had ordered a task force to implement. Prominent among them is the need for adequate funding for embassy security by Congress; the report notes that chronic budget pressure had conditioned State’s managers to reflexively resist spending even on vital security needs.

The board offered a needed corrective to some of the false charges and conspiracy-weaving about Benghazi by Republicans and conservative media. Contrary to claims by Fox News, the investigation found no evidence that a security force at a nearby CIA mission was slow in responding to the attack; it also discounted suggestions that U.S. military assets could have been brought to bear during the attack. In Washington, it concluded, “the interagency response was timely and appropriate.”

That said, important questions about Benghazi remain unanswered — and the most important piece of accountability remains untackled. Though it confirmed that the Benghazi mission suffered an organized terrorist attack that did not, as the intelligence community initially reported, arise out of a demonstration, the board did not attempt to identify who carried out the attack or what motivated it, saying that should be determined by an FBI criminal investigation. But there is little sign of movement in that probe; in a Wednesday statement, House Intelligence Committee Chairman Mike Rogers (R-Mich.) reported “a near total lack of progress bringing these terrorists to justice.”

In her response to the report, Ms. Clinton described “an expanding safe haven for terrorists” in Mali, Libya’s neighbor, and described a “diplomatic campaign” against it. In fact, the administration has been resisting a French plan for more aggressive action, proposing that any military intervention in Mali be put off for up to a year. There may be some good reasons for delay. But the reality is that stronger tools than criminal investigations and diplomacy will almost certainly be needed to neutralize the Benghazi attackers and the networks behind them. The longer the delay, the greater the danger they will strike again.