Photo: Chip Somodevilla/2013 Getty Images

The London Review of Books has published a long piece by Seymour Hersh claiming that the Obama administration failed to acknowledge that a Syrian rebel group was capable of making chemical weapons and could have been responsible for the August 21 sarin gas attack that left hundreds of people dead. “When the attack occurred al-Nusra should have been a suspect, but the administration cherry-picked intelligence to justify a strike against [Syrian President Bashar al-Assad],” writes Hersh, a longtime Pulitzer Prize and Polk Award–winning national security reporter. Of course, that strike was eventually called off, but the report undermines the narrative the administration presented to the American public — and the rest of the world — as they made their case for going after Assad late this summer.

Both President Obama and John Kerry repeatedly said that the administration was aware of the Syrian army’s preparations “three days” before it happened. Hersh writes that that was impossible: An August 29 Washington Post story based on a portion of Edward Snowden’s NSA documents said that the agency was no longer able to monitor conversations between Assad and Syria’s top military officials, which presumably would have included “crucial communications…such as orders for a nerve gas attack.” The NSA materials also showed that there was “a secret sensor system inside Syria, designed to provide early warning of any change in status of the regime’s chemical weapons arsenal.” According to a former senior intelligence official, those sensors didn’t pick up any movement before the attack, making it additionally difficult for the United States to know what was going to occur. Underscoring all this is the fact that the intelligence briefings Obama received in the days before the chemical weapons were used made no mention of Syria.

In a September 4 statement to the AP prompted by the Syrian opposition’s complaints about the American government’s failure to warn them of the impending attack, a spokesman for the Office of the Director of National Intelligence admitted that the administration “did not watch, in real time” as the event unfolded. However, Obama and Kerry continued to use the “three days” line when speaking about bombing Syria. Hersh explains how those statements may have been technically true: “Once the scale of events on 21 August was understood, the NSA mounted a comprehensive effort to search for any links to the attack, sorting through the full archive of stored communications” from military units throughout Syria that, because of their sheer volume and generally “mundane” nature, had not been analyzed before the gassing. But, he points out, that is not what most people thought Obama and Kerry meant.

Additionally, in both public statements and, according to a lawmaker who spoke to Hersh, private briefings with Congress, the administration maintained that the Assad regime was the only entity in Syria with sarin. However, according to an unnamed “senior intelligence consultant” who spoke to Hersh, a June 20 “four-page top secret cable” forwarded to Defense Intelligence Agency deputy director David R. Shedd confirmed that the al-Nusra rebel group, which has ties to Al Qaeda, had “the ability to acquire and use sarin.” Spokesmen for the DIA and Office of the Director of National Intelligence said they were “not aware” of the cable, which they claimed to be unable to locate. The ODNI’s public affairs chief, Shawn Turner, denied that any American intelligence agency “assesses that the al-Nusra Front has succeeded in developing a capacity to manufacture sarin.”

Hersh suggests that the aforementioned sarin sensors may not have gone off because the gas did not come from the Syrian government’s weapons supply, but that of the rebels. Whether or not that is the case, Hersh makes a troubling point about the deal that allowed Assad to avoid a U.S. strike: “While the Syrian regime continues the process of eliminating its chemical arsenal, the irony is that, after Assad’s stockpile of precursor agents is destroyed, al-Nusra and its Islamist allies could end up as the only faction inside Syria with access to the ingredients that can create sarin, a strategic weapon that would be unlike any other in the war zone.” That prospect seems like something worth at least looking into.