The international backlash might not be limited to complaint about rule-breaking; there are serious practical matters to consider, too. For one, whence would the U.S. launch any attacks? The Washington Post reports:
The United States has a broad arsenal already in the region should Trump decide to attack, including dozens of strike aircraft on the USS George H.W. Bush, an aircraft carrier that is deployed to the Middle East and accompanied by guided-missile destroyers and cruisers that can also launch Tomahawk cruise missiles.
Additionally, an amphibious naval force in the region that includes the 24th Marine Expeditionary Unit could muster Harrier jets and Cobra gunship helicopters. The Pentagon also has scores of aircraft in the region flying operations every day against the Islamic State group, including from Incirlik air base to the north in Turkey.
Nations hosting U.S. planes attacking ISIS might not be so eager to be a base for attacks on Assad, but Turkish President Recep Tayyip Erdogan has already said he would support U.S. action, which might answer one question.
Once U.S. aircraft were headed into Syria, they would have to negotiate the problem of Russian troops already there. Though the Kremlin said Thursday its support for Assad is not unconditional, there are Russian forces currently on the ground, along with sophisticated anti-aircraft systems. If American attacks killed Russians, it could spark a much larger diplomatic or military encounter. (The presence of Russian forces in Syria was one reasons some experts dismissed Hillary Clinton’s proposal for a no-fly zone in the country.)
All of this assumes Trump would begin with a barrage of airstrikes. (The U.S. does have limited ground troops already in Syria to fight ISIS, too.) One question is whether the president would pursue a quick strike and then attempt to extricate himself, or try something more sweeping. When Obama was toying with action, he very publicly pursued a limited strategy. Secretary of State John Kerry was widely mocked for saying any attack would be “unbelievably small,” but Kerry’s attempts at reassurance pointed to the central dilemma: What could a highly limited attack really achieve? Obama concluded the answer was not enough. If Trump decided for a small effort, what would the objective be? To kill Assad? And if it didn’t work immediately, what would he do next? Expand his fight? The risk of getting drawn into a protracted war is no less than it was in 2013.
If, on the other hand, Trump sought a more extensive strategy, all of the logistical, legal, and political questions would be even more complicated. Given how new the Trump administration is, and how understaffed it remains, the president can hardly have had time to consider the sorts of planning required for a major bombing campaign, much less a larger war. When Obama joined the intervention in Libya, it came a month into the Libyan civil war and was coordinated with other nations. Even so, that action turned into a catastrophe. The Iraq war was the product of months of planning, and its aftermath was even worse—bloodier and more costly. The Trump administration is giving every indication it’s on a much faster path than either of these.