WASHINGTON — It is either a turning point or a welcome aberration that President Trump found the cruelly extinguished lives of Syrian children to be compelling (or at least contributory) in his decision to use force in Syria. The nerve gas attack by the Bashar al-Assad regime, he said, "crossed a lot of lines for me . . . innocent children, innocent babies — babies, little babies."

Much of Trump's appeal during his presidential campaign was based on dehumanization — the characterization of migrants as criminals and refugees as terrorist threats. This is the first instance I can recall of Trump showing public empathy for the lives of foreigners. It was jarring in its humanity. Trump engaged in the humanization of Syrian war victims. And that merits praise.

In one moment the president also did something that President Barack Obama could not manage in five years — to be provoked or revolted enough to act decisively in Syria. Obama's tolerance for mass atrocities — for the Assad regime's use of weapons of mass destruction, torture, forced starvation and barrel bombs — was rooted in a tendency rather than a doctrine. At every point of decision during years of Syrian protest and civil war, Obama magnified the risks of action and miniaturized the prospect of gain. This series of indecisions fit Obama's inherent cautiousness. But it also added up to a bad case of Iraq War Syndrome — a fear of inalterably escalating engagement.

Until a few days ago, Trump was firmly in the same camp. Before becoming president, he did something of ambitious irrationality — accusing his predecessor of being too engaged on Syria, too tempted by involvement. "What will we get for bombing Syria," he tweeted during Obama's red-line crisis in 2013, "besides more debt and a possible long-term conflict?"

What will we get for bombing Syria besides more debt and a possible long term conflict? Obama needs Congressional approval.

— Donald J. Trump (@realDonaldTrump) August 29, 2013

So how do we explain Trump's head-snapping inconsistency on this issue? It is worth noting that Trump did leave himself an out of sorts — a possible basis for action — buried in his old tweets on Syria. "We don't have the leadership to win wars or even strategize," he argued, raising the possibility that a different president might possess such skills. Trump clearly views himself as the change he has been waiting for.

This, however, is probably too cynical. Seeing the corpses of Syrian children as a private citizen may provoke feelings of anger and helplessness. When a president sees the corpses of Syrian children, he is by no means helpless. When some moral norms are violated, it is not only the perpetrator who incurs responsibility; it is the bystanders as well. It seems that Trump felt this burden. And it is a sign that maybe, just maybe, the office has begun to shape the man.

Whatever his motivation, Trump's military actions have moved beyond the Iraq War Syndrome. And they represent a defeat for global Bannonism — the search for stability through the cultivation of despots and strongmen.

We still have no idea whether Trump's military response was a moral impulse alone or a policy change. A symbol or a strategy. We know that Trump is capable of impulsive ad hockery. There is less reason to be confident he is thinking three, four or five steps down the road. Does this signal a new attitude toward Russia's expanded role in the Middle East or to the status of Assad in Syria's future? Will every future mass atrocity gain such treatment? And why, when you think about it, is the crime of using nerve agents against civilians more heinous than killing them with forced starvation or barrel bombs?

The specter haunting U.S. foreign policy is not so much the Iraq War as the Libya debacle. The imminent destruction of Benghazi provoked a moral and military response from Obama — an air campaign that worked well in its initial stages. But little thought and fewer resources were devoted to the follow-up. And what resulted was a jihadist playground.

The problem with Obama's Syria response was not just its moral bankruptcy or its lack of credibility. It was a woefully inadequate response to the largest strategic and moral challenge of our time — the collapse of sovereignty at the heart of the Middle East, with radiating effects throughout the region, Europe and beyond. And this failure would not have been rectified by a few dozen guided missiles.

Our current president will find that a Tomahawk missile is not the equivalent of a particularly nasty tweet. It is the conduct of war against a foreign power. And it demands a strategy of equal seriousness.