Brian M Downing
The Syrian war took another turn this week as several dozen Idlib civilians were killed by noxious clouds. The victims’ symptoms point to nerve gas, possibly sarin. Subsequent autopsies support this.
World opinion, generally weary of the endless conflict and the numerous atrocities, is angry. For years people have hoped that someone would do something someday. The Idlib attack will lead to a response. But where and by whom?
Syria
The Syrian military is most likely responsible. Damascus and Moscow insist that the nerve gas was stockpiled by rebels and inadvertently released when an airstrike hit a rebel position. This is unlikely – doubly so. The rebels do not have sophisticated laboratories to produce sarin. And the deadly gas is produced by mixing two compounds which would be kept separate until shortly before use. An airstrike cannot fortuitously combine them.
The Assad government’s reasoning behind the attack isn’t known. The war is proceeding well for Damascus – astonishing well given its situation just two years ago. City after city has fallen out of rebel hands.
Assad wants to consolidate control over western Syria, including Aleppo and Idib. He may still hope for a full reconquest but this is unlikely as it would require more years of war, with considerable Russian support, in predominately Sunni regions. Better to solidify control over the Shia regions by intimidating remaining Sunnis – or driving them out.
Russia
It’s unlikely the attack took place without Russian foreknowledge if not approval. This would have risked angering Damascus’s only powerful ally. Russia has no interest in Shia-Sunni enmities, but it does have one in a stable rump state to serve as an ally in the region and to secure Russian military bases at Latakia and Tartus – the latter lying only 75 miles west of Idlib.
Assad’s use of chemical weapons discredits Putin, as he promised to see that Syria disposed of its stockpiles. But Putin denies his ally used nerve gas and will stick to the story of the rebel stockpiles. In any case, the atrocities of Idlib are no more egregious than those of Aleppo a few months ago. High explosives kill civilians as effectively as nerve agents do.
Russia benefits from demonstrating support for ruthless tactics in war. It underscores its willingness to use force – and America and NATO’s lack thereof, at least thus far.
US response
The need to show resolve is clear in American security bureaus. President Trump expressed outrage. UN Ambassador Haley suggested the US may 
respond outside the mandate of the Security Council, possibly unilaterally. A response, probably using cruise missiles, is being weighed by the Pentagon.
One option would be to attack the political and military leadership – a decapitation strike as it’s called. This has visceral attractions but it risks also killing high-ranking Russian officials and generals, who are routinely in Assad and his clique’s proximity. Further, killing Assad and a few regime figures might well lead to the accession of even more ruthless people and dispose them toward even more atrocities.
Another option would be to strike remaining stockpiles of chemical weapons. There would little if any chance of a toxic cloud spreading, as the binary components will not have been mixed. However, the Pentagon might not have such targets identified or properly so. The sites may be based on faulty intelligence, or on false information planted by Syrian or Russian intelligence. This would embarrass the US and divert attention from Idlib.
A third option would be to hit the Syrian air force and crater its runways. This would signal US resolve and also reduce the government’s ability to support troops in the field.
All options risk greater conflict with Russia and will undoubtedly elicit a strong reaction from Putin somewhere in the world.
Israel
An American response could be obviated by Israeli actions. Nerve gas in Syria could fall into the hands of ISIL, al Qaeda, or Hisbollah. There is also concern that the gas used on Idlib was manufactured in Hisbollah labs across the border in Lebanon.
Israel has good relations with Russia based on trade and potential cooperation on settling the Syrian conflict. Though on opposing sides, they share information on each other’s aircraft missions in order to prevent 
errors. Netanyahu is positioned to convince Putin to ensure that Assad’s chemical weapons are eliminated. The implication will be clear to the Russian president.
Israel has been bombing targets inside Syria for years now. Its intelligence networks routinely identify arms caches and convoys, then IDF jets swiftly destroy them. The same sources find IRGC and Hisbollah commanders, with the same result. IDF jets may soon strike more targets inside Syria and perhaps Lebanon as well.
World opinion is usually critical of Israeli military operations. Strikes on Syria, however, whether on chemical weapons sites or simply of a retaliatory nature, would be welcomed in most of the world – this at a time when the image of Netanyahu and his Likud party is very much in need of improvement.
Copyright 2017 Brian M Downing
Brian M Downing is a national security analyst who has written for outlets across the political spectrum. He studied at Georgetown University and the University of Chicago, and did post-graduate work at Harvard’s Center for International Affairs.