NATO chief Mark Rutte said Thursday that North Korea's involvement in Russia's war against Ukraine posed a direct threat to the United States, in a first effort to convince Donald Trump to keep backing Kyiv.
Trump's thumping victory to return to the US presidency has set nerves jangling in Europe that he could pull the plug on vital Washington military aid for Ukraine.
NATO allies say keeping Kyiv in the fight against Moscow is key to both European and American security, and Rutte sought to join the dots for Trump between the conflict and Washington's major foes elsewhere.
"What we see more and more is that North Korea, Iran, China and of course Russia are working together, working together against Ukraine," Rutte told reporters at a European leaders' meeting in Budapest.
"At the same time, Russia has to pay for this, and one of the things they are doing is delivering technology to North Korea, which is now threatening in future the mainland of the US, continental Europe," he warned.
"I look forward to sit down with Donald Trump to discuss how we can face these threats collectively," Rutte said.
North Korea has become one of the strongest backers of Russia's war on Ukraine, and has been accused of recently sending troops to fight alongside Moscow's forces.
Ukrainian President Volodymyr Zelensky told journalists in Budapest that 11,000 North Korean troops were in Russia's western Kursk region and had already sustained "losses".
"North Korea is now, in effect, waging war in Europe. North Korean soldiers are attempting to kill our people on European soil," Zelensky said.
Iran meanwhile is accused of supplying Russia with missiles and drones, and China has been deemed a key backer for keeping technology heading to Russia that Moscow needs to maintain its fight.
Trump has rattled US allies by casting doubt on the tens of billions of dollars in military aid Washington has pumped into Ukraine since Russia's 2022 invasion.
The volatile former reality TV star has sparked fears that he could force Kyiv to accept a peace deal on Moscow's terms after insisting he could end the war "in 24 hours".
Keeping Ukraine's single biggest donor on board is seen by most as essential for ensuring Kyiv stays afloat, especially at a time of political uncertainty in major European powers Germany and France.
On the battlefield Ukraine's fatigued troops are struggling to stave off Russia's advances as they approach three years of full-scale combat.
Europe together has spent around $125 billion on supporting Ukraine, while the United States alone has coughed up more than $90 billion, according to a tracker from the Kiel Institute.
Washington has the deepest weapons reserves and has supplied many of the most effective weapons used in the war.
"Any narrative that can help Trump look more favourably on Ukraine is good and worth trying," said one senior NATO diplomat, speaking on condition of anonymity to discuss sensitive topics.
Many EU leaders meeting at the summit in Budapest sought to downplay the threat of Washington ending its support for Ukraine -- and insisted Europe would keep going regardless.
"Ukraine deserves our support, no matter if we are the United States or Europe, because they were attacked, brutally attacked by the aggressor country," Lithuania's President Gitanas Nauseda said.
"This is not only about Ukraine. This is about rules-based international order, and we have to preserve it."
Outgoing Belgian Prime Minister Alexander De Croo said that if the United States "would decide to change, that does not mean that we need to change".
"That the support for Ukraine stands or collapses with the United States is not true -- European countries play a very determining role in that," he said.
