The U.S. Senate Intelligence Committee’s bipartisan report on the deadly attack in Benghazi makes it clear that the deaths of U.S. Ambassador Christopher Stevens and three other Americans at the diplomatic mission were entirely preventable.

It is a nuanced report, which makes it credible. Criticism of the State Department, then under Hillary Clinton, is blistering. But the committee also blamed the Pentagon, the CIA and other agencies.

“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 U.S. Mission,” it said.

There were multiple warnings and ample evidence of escalating threats to Westerners in the area.

The report faults the CIA for not informing the U.S. military command about an annex it was operating in Benghazi. It found the Pentagon was ill-prepared to defend the compound. And for the first time, Stevens himself was identified as contributing to the failure.

The Defense Department offered increased military protection several times in the months before the Sept. 11, 2012, attack, but Stevens declined. Officials on the ground have to be part of these decisions, but intelligence reports and other warning signs should have trumped the ambassador’s instincts.

The report does little to address charges that the Obama administration misled the public about the attacks because the presidential election was imminent. It did question why intelligence officials took six days to acknowledge that “there were no demonstrations or protests” at the diplomatic compound “before the attacks,” as they had previously reported.

But the committee found no evidence of an al-Qaida plot, as some Republicans persist in theorizing.

The bipartisan conclusion instead was similar to that of a New York Times investigation published several weeks ago. Both said the attack appeared to be opportunistic rather than planned, and it involved numerous terrorist cells and militias. Demonstrations earlier at the U.S. Embassy in Cairo over an anti-Islamic video may have lit the spark.

In a footnote, the committee said it encountered a great deal of resistance from federal agencies to this investigation — especially from the State Department. We hope it backfired. The force of the committee’s blame was not blunted.

The State Department on Wednesday issued an update on improving security at overseas posts.

The diplomatic service always carries risk, but Americans who choose to serve their country in this way deserve all the protection they reasonably can be given. This nation failed Stevens and his colleagues. We hope the unredacted version of this report both points to people who should be held responsible and provides a blueprint for real protection.

This tragedy can be a template for how not to run a mission in a hostile land of deteriorating stability.