Whatever red line Obama and Trump have drawn on the use of chemical weapons, it is by now so muddied by inaction—Saturday’s attack marked the eighth use of poison gas since Trump’s strike last April—that experts argue the U.S. would need to take dramatic new steps to credibly re-establish its leverage. “I actually think that it has to be much stronger and more sustained. I think we have to be careful here not to take on the Russians, you don’t want a conflict between nuclear powers,” Burns told me. “But we can go directly after Assad’s commanders and his airbases from which these attacks are launched and destroy planes on the ground and destroy part of the infrastructure of the Syrian military.”

The former ambassador added that it will be critical that the U.S. form a coalition with its U.S. allies in the Middle East and the Europeans to serve as a bulwark against Russian and Iranian aggression in the region. “We have not been responding to the chemical weapons attacks . . . obviously they thought that they could get away with it,” he said. “The real trick here is that we have to be careful because we don’t want to launch into a commitment that is so big that we get stuck in the Middle East again as we did in Iraq. If we try to take down, overthrow the Assad government, no matter how many of us would like to see Assad leave, he is not going to leave and he is in a strong position right now. But we can help the Syrian Kurds in the North, we can help the refugees, we can protect victims—or try to—of chemical weapons. We should do all those things. We should not leave the field to the Russians and the Iranians in my judgement.”

Others cautioned against another missile attack. “The last strike had no strategic or tactical utility; it didn’t help the humanitarian situation on the ground; it didn’t alter the strategic situation on the ground; it didn’t undermine the Assad regime’s control; it didn’t fight terrorism. It was really just this symbolic show, demonstrating that we are still the policeman of the world. It didn’t have any tangible impact on the conflict,” Glaser said. “We need to ask how are the means connected to the ends? Whatever tactics we use against the Assad regime in retaliation for this, how is that connected to some objective that we have? I don’t even see what the objective is other than we feel embarrassed for not acting.”

There is also the question of Trump’s executive authority to launch a military strike against the Assad regime. “President’s aren’t magically able to bomb any country that they want on their own whim. It requires legal authorization,” Glaser said. Congress was divided over whether the president had the legal authority to launch the targeted strike last April. While Senate Majority Leader Mitch McConnell and Senate Foreign Relations Chairman Bob Corker said the attack didn’t warrant an Authorization for Use of Military Force, or A.U.M.F., from Congress, which Trump did not have, others argued the opposite. “We have to think about all the consequences,” Congressman Justin Amash said at the time. “It’s critical under our system of government that these types of actions have congressional approval, because they are acts of war, and what begins as a set of strikes on one night can quickly escalate into a much broader conflict.”

Under international law, any strike launched by the U.S. against Syria would require a Security Council resolution—which it doesn’t have, and is unlikely to get. “The chances of the U.N. resolving this awful situation are basically zero,” said Richard Gowan, a U.N. expert and professor of International and Public Affairs at Columbia University. “Russia has consistently blocked Western efforts to call Assad out over chemical weapons over the last year. They are already signaling that they will hang tough this time.” What happens next, he said is inevitable: “[Nikki] Haley, the French, and the Brits will have a huge row with the Russians. They will then table a resolution demanding an investigation of the events in Ghouta. The Russians will veto it, possibly with Chinese support. Washington will then argue that the U.N. route is blocked, so it has no choice but to use force. . . . Right now, the council offers no real solutions to the endgame in Syria.”