After keeping Donald Trump happy with a pledge to up defense spending at NATO's summit, Europe is now bracing for a key decision from the US president on the future of American forces on the continent.
Washington is currently conducting a review of its military deployments worldwide -- set to be unveiled in coming months -- and the expectation is it will lead to drawdowns in Europe.
That prospect is fraying the nerves of US allies, especially as fears swirl that Russia could look to attack a NATO country within the next few years if the war in Ukraine dies down.
However, the alliance is basking in Trump's newfound goodwill following its June summit in The Hague, and his officials are making encouraging noises that Europe will not be left in the lurch.
"We've agreed to no surprises and no gaps in the strategic framework of Europe," said Matthew Whitaker, US ambassador to NATO, adding he expected the review to come out in "late summer, early fall".
"I have daily conversations with our allies about the process," he said.
While successive US governments have mulled scaling back in Europe to focus more on China, Trump has insisted more forcefully than his predecessors that the continent should handle its own defense.
"There's every reason to expect a withdrawal from Europe," said Marta Mucznik from the International Crisis Group. "The question is not whether it's going to happen, but how fast."
When Trump returned to office in January many felt he was about to blow a hole in the seven-decade-old alliance.
But the vibe in NATO circles is now far more upbeat than those desperate days.
"There's a sanguine mood, a lot of guesswork, but the early signals are quite positive," one senior European diplomat told AFP, talking as others on condition of anonymity.
"Certainly no panic or doom and gloom."
'Inevitable'
The Pentagon says there are nearly 85,000 US military personnel in Europe -- a number that has fluctuated between 75,000 and 105,000 since Russia's 2022 invasion of Ukraine.
"I think it is inevitable that they pull out some of their forces," a second European diplomat told AFP.
"But I don't expect this to be like a dramatic overhaul. I think it's going to be gradual. I think it's going to be based on consultations."
Trump's first target is likely to be the troops left over from a surge ordered by his predecessor Joe Biden after Moscow's tanks rolled into Ukraine.
Officials say relocating the rump of that 20,000-strong deployment would not hurt NATO's deterrence too much -- but alarm bells would ring if Trump looked to cut too deep into personnel numbers or close key bases.
The issue is not just troop numbers -- the US has capabilities such as air defenses, long-range missiles and satellite surveillance that allies would struggle to replace in the short-term.
"The kinds of defense investments by Europe that are being made coming out of The Hague summit may only be felt in real capability terms over many years," said Ian Lesser from the German Marshall Fund think tank.
"So the question of timing really does matter."
'Inopportune moment'
Washington's desire to pull back from Europe may be tempered by Trump now taking a tougher line with Russia -- and Moscow's reluctance to bow to his demands to end the Ukraine war.
"It seems an inopportune moment to send signals of weakness and reductions in the American security presence in Europe," Lesser said.
He also pointed to Trump's struggles during his first term to pull troops out of Germany -- the potential bill for relocating them along with political resistance in Washington scuppering the plan.
While European diplomats are feeling more confident than before about the troop review, they admit nothing can be certain with the mercurial US president.
Other issues such as Washington's trade negotiations with the EU could rock transatlantic ties in the meantime and upend the good vibes.
"It seems positive for now," said a third European diplomat.
"But what if we are all wrong and a force decrease will start in 2026. To be honest, there isn't much to go on at this stage."
