As talks swirl over U.S. President Donald Trump's commitment to NATO, both sides of the Atlantic now agree: Europe needs to step up and take more responsibility for its own defense.
The shift away from relying on America's might will be a key focus as leaders from the 32-country alliance meet for a summit in Ankara this week.
From what's happening to how far it could go, here are some of the key issues:
Trump has not been shy about his criticisms of NATO – most recently lashing out at European allies over their response to his war against Iran.
The mercurial leader has repeatedly undercut faith in the U.S. by casting doubt on whether he would stand by the alliance's Article Five mutual defense clause.
But it's not just words coming from Washington now.
Since Trump's return to power, his administration has made it crystal clear it wants Europe to take the lead on defending the continent as the U.S. focuses on other parts of the globe.
Washington rattled NATO by abruptly announcing in May that it would pull 5,000 troops from Germany and halt a deployment to Poland, before flip-flopping.
The Pentagon then told allies it was scaling back the military assets it puts at NATO's disposal and has announced a six-month review of its forces in Europe.
"We're doubling down on our effort to make NATO what it always was supposed to be, a balanced alliance with Europe in the lead for its own defence," U.S. Defence Secretary Pete Hegseth said.
European countries started ramping up military budgets after Russia's 2022 invasion of Ukraine – but pressure from Trump sent those efforts into warp speed.
After decades of underinvestment by Europe, NATO leaders agreed at a summit last year to increase defense-related spending to 5% of gross domestic product (GDP) by 2035.
"There's truly a revolution going on in the alliance," said one European diplomat, speaking on condition of anonymity. "This burden shifting that we decided will fundamentally change this alliance."
While the U.S. remains by far the biggest spender, Europe and Canada together are aiming in the coming years to match Washington's budget.
Powerhouse Germany has led the way, while spending by countries closest to Russia is already near NATO's target.
Across the alliance, there is now an understanding that the U.S. pulling back is inescapable – and that won't change even once Trump leaves.
"It's not about Trump. It's a structural long-term change," said Claudia Major of the German Marshall Fund think tank.
"It can be shaped but not avoided."
While Europe can already fill in some of the gaps Washington is leaving in NATO's defense plans, key assets such as long-range missiles will take time to substitute.
"It's very clear that the U.S. role is changing anyway, and the main hope is to do damage control and to get predictability," said Major.
Despite the headline-grabbing spats and announcements, the changes on the ground have so far not been too dramatic.
The U.S. still has some 80,000 troops in Europe, and there are plenty of pro-NATO voices in Washington who want them to stay.
America's nuclear umbrella also remains the ultimate safeguard for European security and the Trump administration is not talking about stepping that back.
There has been some shuffling of NATO commanders, with Europeans now taking over all the regional headquarters.
But the United States still holds the top overall military post and also has control over the air, land and sea commands.
"The alliance is slowly transforming itself. In a couple of years, Europe will be much more relevant," said a second diplomat.
For now, no one at NATO is publicly talking about the Europeans needing to go it alone, or replacing the alliance entirely.
At the summit in Ankara, diplomats say the leaders are set to call for a "stronger Europe in a stronger NATO," and the aim is to keep the United States as engaged as possible.
Going forward, Europe may increasingly look to bind Ukraine – and its battle-tested forces – more closely into the continent's security architecture.
But with the path to Kyiv joining NATO firmly blocked for now, those efforts are mainly focused on Ukraine's push for EU membership.
