By stating that Syrian President Bashar al-Assad had used chemical weapons, Brig. Gen. Itai Brun, the director of Israel’s Military Intelligence Research Department, cornered the Americans. Washington finally — and very tentatively — admitted that such weapons had been used. If Israeli Prime Minister Benjamin Netanyahu planned to ambush the Americans, it was a phenomenal success. From an Israeli standpoint, this was a chance to test America's supposed "red line," although it's doubtful that American recognition of the use of chemical weapons against Syrian civilians will culminate in a military intervention.

On the afternoon of March 19, as Syrian insurgents began to disseminate photos of an attack by the Syrian military in Aleppo, Israeli intelligence bodies already knew that nerve agents had been used against civilians, and probably not for the first time. That intelligence was based on the analysis of video footage following the attack, which documented the victims' symptoms, but it was also based on intelligence Israel had obtained.

As is common practice in such cases, Israel’s intelligence agencies shared this information with their American and European counterparts to compare the data. The Israelis and the British reached a clear conclusion: Assad’s military had used sarin nerve gas against civilians, and not for the first time. The Americans remained skeptical. Having defined the use of chemical weapons as a "red line," they would have been called upon to intervene in Syria after acknowledging this intelligence. Aware of the administration’s unwillingness to get involved in the Syrian conflict, American intelligence agencies remained skeptical, in the hope of not embarrassing the administration. Moreover, American intelligence officials say that after their false assessments about Iraqi weapons in the lead-up to the Iraq intervention, they wanted to exercise greater caution in this case.

The American explanation is perhaps understandable, but its conduct is reminiscent of previous occasions. While the bodies of hundreds of thousands of Tutsi were piling up in Rwanda, the Clinton administration forbade its officials to use the term “genocide” lest it be forced to intervene. In the case of Aleppo, too, administration officials were careful to state that there was no conclusive evidence to suggest the use of chemical weapons in Syria, even as Senate Intelligence Committee members, who were briefed on the matter one day after the incident, were fully convinced that such weapons had been used.