"Why is this so crucial that Putin will not get his way? Because you will have an emboldened Russia on our border... and I'm absolutely convinced it will not stop there," Rutte told reporters in Brussels.

"It is then posing a direct threat to all of us in the West," he said.

As Ukraine marks "1,000 days of the unprovoked full Russian onslaught", Rutte said ministers would "discuss how we can help Ukraine to prevail: that means more aid, more money".

"We need simply to do more. We have to ramp up the defence industry," he said.

Two and a half years after Moscow's 2022 invasion of Ukraine, now 23 of the 32 NATO members reach the target of spending two percent of gross domestic product on defence -- up from just three a decade ago.

But the growing consensus is that Europe will have to do more to make sure it can stand on its own -- with Donald Trump's return to the US presidency fuelling fears he could pull the plug on vital aid for Ukraine.

"Two percent -- great that we have achieved it on the European side of NATO overall, but it is not enough, it is clearly not enough," Rutte said.

NATO's new chief has broadly downplayed fears over Trump's return but has also sought to join the dots between the Ukraine war and Washington's foes elsewhere in a pitch to keep the Republican engaged.

"The horrifying fact is this: that four countries are working together," Rutte said. "It's not just Russia. It's North Korea being involved. It's China being involved. It's Iran being involved."

Russian missile technology heading to North Korea as part of this emerging alliance "poses a direct threat, not only to us, but also to South Korea, to Japan, and even to the US mainland," Rutte reiterated.