President Donald Trump has demanded Washington's NATO allies ramp up their military spending to five percent of GDP, a level that not even the United States currently hits.

Schoof said Rutte had written to NATO's 32 member countries calling for them to reach 3.5 percent of GDP on "hard military spending" and 1.5 percent of GDP on "related spending, such as infrastructure, cybersecurity and other things" over the next seven years.

Trump is piling the pressure on Europe and Canada to ratchet up NATO's spending target at a summit in The Hague next month.

Rutte on Friday refused to confirm the figures being debated, but said "internal discussions" were taking place within NATO.

Diplomats within the alliance, speaking on condition of anonymity, said the proposal circulated last week envisioned increasing direct military spending by 0.2 percent each year to 2032.

They said the discussions over the new target were at an early stage and there were no clear signs yet that there would be consensus for the figures.

The parameters of what could be included in the 1.5 percent of loosely related defence spending were still to be defined, they said.

Trump has long accused Washington's allies of underspending on their defence and taking advantage of US largesse.

The volatile leader has gone so far as to threaten not to protect countries that do not spend enough on their military in his eyes.

European countries have ramped up their defence spending since Russia's invasion of Ukraine in 2022, but Rutte says they must go considerably higher to ward off Moscow.

Last year 22 of NATO's 32 allies hit its current threshold of spending two percent on their militaries.

A string of countries such as Italy, Spain, Canada and Belgium that still lag below that level have pledged to reach it in 2025.

The United States last year spent 3.19 percent of its GDP on defence, behind eastern flank countries Poland, Estonia and Lithuania close to Russia.

But Washington remains by far the biggest military spender in NATO in absolute terms, accounting for 64 percent of all defence expenditure last year.