President Trump jabs at the Russian leader with threats; Vladimir Putin responds with flattery. But there are notable signals in their jousting, including a revived discussion about nuclear arms control.

But there’s a surprising case in which Europe is cautiously optimistic: Ukraine. Trump’s threat to Russian President Vladimir Putin on Wednesday to impose new tariffs and sanctions on Moscow if it didn’t reach a deal to stop the war sent a welcome message to European allies and other Ukraine supporters.

Predictably hawkish on Iran, suddenly friendly with Xi, belligerent when it comes to allies Mexico and Canada and Denmark—Trump doesn’t have anything near a predictable worldview. The only hope is that he and his appointees will attempt to ensure that American interests are served,