US President Donald Trump swept into Nato’s Hague summit on Tuesday, with allies hoping a pledge to ramp up defence spending will keep the mercurial leader of the military superpower committed to protecting them.

Trump joined leaders from Nato’s 31 other members to kick off the two-day gathering with a dinner hosted by Dutch King Willem-Alexander in the ornate Orange Hall at his royal residence.

The alliance hopes to keep Trump bound to its mutual defence vow by meeting his demand for a headline figure of five per cent of GDP on defence spending.

But Trump refused to say he was committed to Nato’s Article Five clause and protecting Europe in comments that are likely to rattle his counterparts on the continent.

“Depends on your definition. There’s numerous definitions of Article Five,” Trump told journalists aboard Air Force One. “I’m committed to being their friend.”

(Front, from left) US President Donald Trump, Dutch King Willem-Alexander and Dutch Queen Maxima pose for a picture with Nato heads of state and governments at Huis ten Bosch Palace in The Hague on Tuesday. Photo: Reuters

(Front, from left) US President Donald Trump, Dutch King Willem-Alexander and Dutch Queen Maxima pose for a picture with Nato heads of state and governments at Huis ten Bosch Palace in The Hague on Tuesday. Photo: Reuters

To keep Trump on board, Nato members have thrashed out a compromise deal to dedicate 3.5 per cent to core military needs by 2035, and 1.5 per cent to broader security-related areas such as cybersecurity and infrastructure.