US President Donald Trump sowed doubt on his intentions around NATOs Article Five clause, the political commitment by allied countries to come to the aid of any member whose sovereignty or territory may be under attack. The two-day NATO summit is taking place in The Hague and will end on Wednesday.

Will he play nice? That's the question forNATOleaders nervously waiting to see if a carefully choreographed show to please US PresidentDonald Trumpwill pay dividends when the alliance summit gets down to business on Wednesday.

Every precaution is in place to avoid a Trump blow-up at the Hague summit, from giving him credit for a historic spending deal to keeping the meeting short and sweet.

But that did not stop the volatile US leader launching a pre-summit grenade as he crossed the Atlantic on Air Force One, casting doubt on the very foundation of the 32-member alliance.

He refused to state his commitment to NATO's Article Five clause, the basic agreement that says an attack on one member is an attack on all.

"Depends on your definition. There's numerous definitions of Article Five," Trump told journalists in comments sure to rattle the European allies he dined with upon arrival Tuesday night.

"I'm committed to being their friend," he said.

Read moreNATO summit opens amid discord over defence spending and Ukraine

In a message probably not designed for public consumption, NATO Secretary GeneralMark Rutteheaped flattery on Trump, praising him for bringing everyone on board for the spending hike.

"Europe is going to pay in a BIG way, as they should, and it will be your win," Rutte wrote in a gushing, caps-filled missive to Trump, who promptly posted it on social media.

"You are flying into another big success in The Hague this evening. It was not easy but we've got them all signed on to five percent," wrote Rutte.

NATO allies are to sign off Wednesday on a pledge to spend 3.5 percent ofGDPon coredefencespending, plus another 1.5 percent on broader security-related areas such as cybersecurity and infrastructure.

"The Europe of defence has finally awakened. Tomorrow the summit will set historic new spending targets for NATO allies," saidEuropean CommissionPresidentUrsula von der Leyen.

'This is incredible'

The spending hike is designed to keep Trump engaged with the alliance, after his return to power sparked fears he could blow up the seven-decade-old organisation.

Trump has long groused that European countries pay too little for their own security, upended byRussia's war inUkraine.

Spainwas the main hold-out on the five-percent target, complaining that spending that amount on defence was "unreasonable" and drawing Trump's ire in the process.

Trump took fresh aim at Madrid en route to The Hague, calling its stance "very unfair" and posting a graphic entitled "Spain threatens to derail NATO summit" showing the relative outlay of alliance members.

"The United States is at almost $1 Trillion Dollars This is incredible!" he wrote on Truth Social.

Spain has been one of the lowest-spending NATO countries on defence in relative terms.

The country is only set to hit the current NATO target of two percent this year after a 10-billion-euro injection.

"Will be discussing it soon with the members of NATO," said Trump ominously.

Rutte has stressed the spending hike billed as "historic" is needed to keep Russia in check, but even here Trump threatens to spoil NATO unity.

He has turned Western policy on Ukraine on its head, reaching out to Russian PresidentVladimir Putinand maintaining a volatile relationship with Ukraine's leaderVolodymyr Zelensky.

"Russia must see that Ukraine will not be left alone and that Europe will not back down," Zelensky told the Dutch parliament ahead of the summit.

Trump and Zelensky are slated to have a tete-a-tete inThe Haguewith officials hoping to avoid a bust-up like their infamous Oval Office shouting match.

Unlike previous summits, Zelensky has not been invited to the main working session of the leaders cut to two and a half hours, reportedly a nod to Trump's dislike of lengthy talks.

Rutte said allies would send the message that support for Kyiv was "unwavering and will persist".

But despite his insistence that Ukraine's bid for membership remains "irreversible", NATO will avoid any mention of Kyiv's push to join after Trump ruled it out.

One European diplomat put it succinctly. "We have a completely unpredictable US president."

"We are hoping there won't be an ill-timed comment that is all anyone remembers. Everything has been done to reduce this risk," this official said.

(FRANCE 24 with AFP)

Originally published on France24