The horrifying images of the gas attack in Idlib on April 4 shocked many in Israel and led to a wide range of responses in the country, including a call for an emergency Cabinet session by Minister Naftali Bennett.

The Israel Defense Forces' (IDF) Intelligence Division and the Mossad seem to have suffered the greatest shock, however, since they are responsible for assessing the chemical weapons capabilities of the Syrian regime. The fact that the regime is suspected of using sarin nerve gas against the population casts their current assessments into doubt and challenges Israel's working assumption about when Syrian President Bashar al-Assad might use any chemical weapons still in his possession. Just two weeks ago, two senior intelligence sources told Al-Monitor that Assad has very limited chemical weapons capacities, mainly chlorine gas. These weapons were described as "neutralizing," i.e., they can kill their targets but not on a wide scale. Photos from Idlib contradict this statement.

Before Syria reached a chemical weapons disarmament agreement with the world powers in September 2013, the IDF assessed that Assad would only use his chemical weapons against Israel if his regime found itself "with its back against the wall." The disarmament agreement, which was only signed after US President Barack Obama deliberated over whether he should embark on military action against Syria's chemical weapons stockpiles, was received with optimism in Israel.

Both the IDF's Intelligence Division and the Mossad concluded that the agreement had been fulfilled in its entirety, and that Assad did, in fact, forgo this strategic asset. According to intelligence sources, Assad was concerned that an American cruise missile and aerial assault would lead to the final collapse of his regime. In other words, he did have "his back against the wall," and decided to give up his chemical weapons arsenal to survive. Israel believed that the Syrian regime kept only "residual" chemical capabilities, i.e., something symbolic, or an "emergency supply" of chemical weapons, to be used only if Assad is forced to flee for his life. The same Israeli assessment also claimed that some 98% of Assad's arsenal of sarin or VX nerve gas (about 1,300 tons) no longer existed.