NATO allies are gathering in Washington confronting the prospect that the military alliance’s most ardent critic, Donald Trump, may seize back power.

NATO – made up of 32 European and North American allies committed to defending each other from armed attack – will stress strength through solidarity as it celebrates its 75th anniversary during the summit starting Tuesday (local time).

Event host US President Joe Biden, who pulled allies into a global network to help Ukraine fight off Russia’s invasion, has called the alliance the most unified it has ever been.

But behind the scenes, a dominant topic will be preparing for possible division, as the power of far-right forces unfriendly to NATO grows in the US and other countries, including France.

The changing situation raises concerns about how strong support will stay for the alliance and the military aid that its members send to Ukraine.

At the presidential debate in June, Biden asked Republican challenger Trump: “You’re going to stay in NATO or you’re going to pull out of NATO?”

Trump’s only response was to tilt his head in a shrug.

Biden’s dire debate performance set off a frenzy about whether the 81-year-old President is fit for office or should step aside as the Democratic candidate.

Even before the debate, European governments were deep in consultations on what they could do to ensure that NATO, Western support for Ukraine and the security of individual NATO countries will endure should Trump win back the presidency in November and temper US contributions.

Some Americans and Europeans call it “Trump-proofing” NATO – or “future-proofing” when the political advances of other far-right political blocs in Europe are factored in.

NATO chief Jens Stoltenberg sidestepped questions on Friday, local time, about Biden’s health, saying one reason for NATO’s success was that it stayed out of domestic political issues, Reuters reported.

Summit looks ‘gloomy’

This week’s summit, held in the city where the mutual-defence alliance was founded in 1949, was once expected to be a celebration of NATO’s endurance.

Now, a European official said, it looks “gloomy”.

There are two reasons for the gloom: Russian advances on the battlefield in the months that Trump-allied congressional Republicans delayed US arms and funding to Ukraine.

And the possibility of far-right governments unfriendly to NATO coming to power.

Rachel Rizzo, a senior fellow on NATO with nonpartisan think tank the Atlantic Council, said she had blunt message for Europeans: “Freaking out about a second Trump term helps no one”.

For allies at the summit, she said, the key will be resisting the temptation to dwell on the details of unprecedented events in US politics and concentrating on readying Western military aid for Ukraine and preparing for any lessening of US support.

Trump would get America out

Trump, who before and after his presidency has spoken admiringly of Russian President Vladimir Putin and harshly of NATO, often focuses his complaints on the US share of the alliance’s costs.

Biden, as a US senator in 1997, warned that if there were any sense other NATO allies were “taking the United States for suckers, the future of the alliance in the next century will be very much in doubt”.

The 1991 collapse of the Soviet Union lulled the West into thinking the Russian threat had been neutralised, leading to military spending cuts.

Now, NATO allies are bolstering their forces against any wider aggression by Putin, and a record 23 nations in NATO are meeting defence-spending goals.

Trump’s former national security adviser, John Bolton, said Trump in a second term would work to get the US out of NATO.

The US Congress passed legislation last year making that harder, but a president could simply stop collaborating in some or all of NATO’s missions.

Biden forges on

Biden was at a black church and rallying with union members on Sunday (local time) in the critical swing state of Pennsylvania, trying to quell a growing clamour from within in his own party to bow out of the race.

He was due to return to Washington later in the day ahead of the three-day NATO summit.

The campaign appearances followed a call with campaign surrogates, where Biden reiterated that he had no plans to step aside, while urging unity among top Democrats.

But he also listened to concerns and feedback, according to two people who spoke on condition of anonymity to discuss private conversations.

Biden pledged on the call to campaign harder and to hit the road more frequently, taking his message to voters more directly.

The focus could shift more to Russia’s war in Ukraine than questions about Biden’s re-election campaign, but the 81-year-old’s political situation remains precarious.

Five Democratic lawmakers have called on him to abandon his re-election bid ahead of November. More could do so in coming days, as Congress reconvenes.

Biden got a weekend boost from other key Democrats who had raised previous questions but now have moved to support him, led by Speaker Nancy Pelosi and Representative James Clyburn of South Carolina.

Still, with the Democratic convention approaching, the short term is especially critical.

-with AAP