The death of the Islamic State’s leader in a daring nighttime raid vindicated the value of three traditional American strengths: robust alliances, faith in intelligence agencies and the projection of military power around the world.

But President Trump has regularly derided the first two. And even as he claimed a significant national security victory on Sunday, the outcome of the raid did little to quell doubts about the wisdom of his push to reduce the United States military presence in Syria at a time when terrorist threats continue to develop in the region…

Mr. Trump’s approach to the region has never been consistent, but he has struck consistent themes. The first is that the United States does not need to keep forces in the region to reach out and kill its enemies. The high price of occupation, rebuilding and vacuum-filling, he suggests, can be paid by allies, or by Russians, Turks and even the Syrian government of Bashar al-Assad…

But the story of Mr. al-Baghdadi’s demise is more complex. He was living in territory that was essentially ungoverned space, dominated by two different Qaeda groups — Mr. al-Baghdadi’s rivals — and now an emerging territory for ISIS fighters on the run. The Syrians and the Russians control the airspace.