But in fact, the move had been in the works for more than a year. Fearing U.S. abandonment, the Kurds opened a back channel to the Syrian government and the Russians in 2018, and those talks ramped up significantly in recent weeks, American, Kurdish and Russian officials told The Associated Press.

“We warned the Kurds that the Americans will ditch them,” Russia’s ambassador to the European Union, Vladimir Chizhov, told Russia’s Tass news agency on Monday.

The switch in allegiances is a stark illustration of how American foes like Russia and Syria are working steadily to fill the vacuum left by President Donald Trump’s retreat in the region. It also betrays the anxiety that U.S. allies across the globe now feel in the face of Trump’s seemingly impulsive foreign policy decisions, which often come as a surprise to allies and critics alike.