- A potential second term for Donald Trump has fueled discussions over the future of the US's role in NATO.
- Trump has previously questioned the value of the alliance and threatened to leave it.
- Experts say Europe now needs to take more control of the running of the alliance.
It was a rather tense atmosphere at the NATO 2024 summit in July.
As President Joe Biden, then still in the presidential race, hailed the alliance's continuing unity in the face of Russia's invasion of Ukraine, the shadow of his predecessor loomed large.
Donald Trump "hangs over every conversation here," one unnamed Eastern European diplomat told the BBC.
A potential second term in the White House for Trump has fueled speculation over the future of the US's role within NATO, as Trump has long been skeptical of the alliance and has repeatedly threatened to leave it.
While that seems unlikely, Europe would nevertheless face the prospect of an "America First" policy should he be reelected in November, with the former president likely to demand that European countries spend significantly more on NATO.
Dan Caldwell, a public policy advisor at The Defense Priorities Foundation, told Business Insider that "Europe needs to wake up to the fact that regardless of who is the next US president, the United States has real limits on its power."
The US's ability to keep troops in Europe and supply arms to Ukraine is "not sustainable indefinitely," Caldwell said, citing national debt, inflation rates, a constrained industrial base, and military recruitment struggles.
While not convinced that Trump would withdraw from NATO, Caldwell said that the US could use incentives to get European countries to bolster their militaries.
"The best way to do that is by withdrawing troops from Europe and making clear that we are rolling back our force posture in Europe," he said, adding that he believed it was "not a bad thing if the United States encourages more European strategic autonomy."
"For the Europeans, there's a lot of talk about Trump-proofing their defense," Caldwell said. "In reality, they need to America-proof their defense in the sense that they can no longer rely on America to continue to cut a blank check to Ukraine and to secure their own backyard regardless of who is US president."
European countries have already started to ramp up military spending.
Defense figures released in February showed what NATO Secretary General Jens Stoltenberg described as an "unprecedented rise" of 11% in defense spending in 2023 across the alliance's European members and Canada.
"In 2024, NATO Allies in Europe will invest a combined total of 380 billion US dollars in defence. For the first time, this amounts to 2% of their combined GDP," Stoltenberg said.
"We are making real progress: European Allies are spending more. However, some Allies still have a ways to go. Because we agreed at the Vilnius Summit that all Allies should invest 2%, and that 2% is a minimum," he added.
Countries bordering Russia, including Finland and the Baltics, have been particularly incentivized to boost their defense spending.
"In Latvia and in my neighbors, we go full out," former Latvian Prime Minister Krišjānis Kariņš said in March. "We invest in our own defense, budgeted 2.4% this year; it looks like we're going to hit 3% this year, and we will be going beyond that in the future as well."