Syrian Airstrikes Leave Key Questions About President Trump’s Intentions Unanswered

President Trump’s airstrike against Syria Thursday may have established a credible deterrent to Bashar al Assad’s future use of chemical weapons, at least in the short term. But the long-term effects of setting a new American red line for the use of chemical weapons are far less certain.

In justifying the airstrikes, Secretary of State Rex Tillerson said they were designed to prevent further chemical weapons attacks in Syria and possibly elsewhere. Assad is “normalizing the use of chemical weapons, which may then be adopted by others,” Tillerson said, “So it’s important that some action be taken on behalf of the international community to make clear that the use of chemical weapons continues to be a violation of international norms.”

That rhetoric and the decision to strike contrasted sharply with Trump’s campaign promises, which offered generally soft rhetoric on the Assad regime and pro-Russia positioning on Syria. In general, Trump projected a lower level of U.S. involvement in the humanitarian problems outside the nation’s borders. By forgoing Congressional approval, let alone U.N. consultation, the strike also pressed the outer boundary of the law. Blowing past those constraints, Trump and his Secretary of Defense, James Mattis, showed a perhaps surprising commitment to deter the use of chemical weapons relative to other policy priorities.

But the deterrence could diminish with time. When last threatened by the U.S., the Assad regime temporarily ceased use of chemical weapons, and even agreed to remove its chemical stockpiles from the country. But once the threat of international intervention waned, the Assad regime decided once again to test the international order. The Trump attack sets the U.S. on an uncertain path if Assad does decide in the future to text American resolve with another attack.

The attack came in response to the use of sarin, the deadly and gruesome agent apparently used at Idlib. Left unresolved is what the American response will be if the Assad regime returns to using the less toxic chlorine gas that he has deployed elsewhere. And if Assad does test Trump, either with sarin or another agent, the next decision may be harder.

In 1999, then-President Bill Clinton launched unilateral air strikes in Kosovo in retaliation for humanitarian violations by the Serbian regime of Slobodan Milosevic. The immediate consequence was a massive round of ethnic cleansing that the U.S. and its allies had sought to avoid, and a hunkering down of Serbian forces in Kosovo. Clinton had to escalate his airstrikes over the following weeks, and Milosevic only complied with U.S. demands to pull out of Kosovo when the U.S. appeared ready to deploy ground forces.

Trump has already moved to increase U.S. forces operating in and around Syria, and is receiving detailed plans from the Pentagon for an escalated fight against ISIS there and in Iraq. But much of the American public, and some in his own party, are wary of being drawn further into the messy civil war.

Which means Trump’s relatively low cost success in punishing Assad’s use of sarin may be a one time thing. As the effect wears off, events could pit Trump’s commitment to deterring chemical weapons use against the political challenge of a deepening, costly commitment to fighting in Syria.