The hitch, from Turkey’s perspective: American forces were with the Kurds, and had expressed commitments to the Kurds; moving against them would have required coming into direct confrontation with the soldiers of a NATO ally. If this helped restrain Erdogan from moving in over the months he was threatening to do it, the calculation changed on Sunday. No more U.S. forces, no more hitch.

“Look, Turkey is a large country,” a senior U.S. administration official told reporters Monday as a bipartisan uproar flared, with politicians and commentators across the political spectrum condemning what they called a betrayal of America’s best friends against ISIS. “It’s got a big military … and they’re a NATO ally. So, you know, the United States is not in a position to, and will not be in a position to, fight Turkey over, you know, any actions that it takes with respect to Syria.”

This person continued: “The president has made it very clear, you know, there should be no untoward action with respect to the Kurds or anyone else.”

What the president would consider “untoward” was unclear, but the kickoff of the Turkish bombardment today stoked panic in Washington as well as northeast Syria. “Pray for our Kurdish allies who have been shamelessly abandoned by the Trump Administration,” tweeted Senator Lindsey Graham, typically a vocal ally of the president. Graham vowed to lead an effort in Congress to make Erdogan “pay a heavy price.”

But Erdogan might not care. Turkey endured sanctions for some of the two years in which the country imprisoned the American pastor Andrew Brunson, then released him last year at Trump’s urging. Turkey has also continued to risk sanctions over its purchase of a Russian air-defense system, though none have yet been imposed—and has kept the system, even though the Defense Department has tried to punish Turkey by refusing to deliver next-generation fighter jets.

Soner Cagaptay, a Turkey expert at the Washington Institute for Near East Policy, told me the incursion might be limited, as Turkish forces seek to break up the swath of territory Kurdish forces hold in northeastern Syria, as they did with two previous interventions. He said that today’s attacks dispel a persistent myth among U.S. decision makers that Turkey only threatens to attack the Kurds in Syria and never actually does: Turkey has done so three times as of today. In The Washington Post yesterday, a spokesman for Erdogan articulated Turkey’s long-standing position: “Turkey has no ambition in northeastern Syria except to neutralize a long-standing threat against Turkish citizens and to liberate the local population from the yoke of armed thugs.”

A spokesman for the Kurdish forces had reported two civilian deaths as of early Monday afternoon. General Joseph Votel, the former head of the U.S. military’s Central Command, which oversees American forces in the Middle East, said at a think-tank event yesterday that it was likely the Kurds would leave the area once it was clear they were outmatched. He said that he was disappointed with the decision to pull back and that it would not have been the military advice he would have given the president. Of his own experience with Kurdish forces, he said, “They protected us every day.”