On the campaign trail, Trump has threatened not to protect Nato members who do not spend enough on defence and promised to cut a quick deal with Putin to put an end to the war in Ukraine
Nato's new Secretary General Mark Rutte gestures as he addresses the media during a press conference at Nato headquarters in Brussels on Tuesday. AFP
Nato's new chief Mark Rutte on Tuesday downplayed fears over the impact of a potential Donald Trump victory in upcoming US elections and pledged to keep backing Ukraine, as he assumed leadership of the world's most powerful military alliance.
The former Dutch prime minister steps into the role at a pivotal moment, as Russia presses its war in Ukraine, China flexes its growing might -- and just weeks before voters in the United States head to the polls.
"I'm determined to prepare Nato for the challenges of the future," Rutte said as he formally took over as secretary general from Norway's Jen Stoltenberg at Nato's Brussels headquarters.
The outcome of the November 5 vote is set to be the straight-talking 57-year-old's first major test -- and will shape his initial four-year term at the helm.
On the campaign trail, US former president Trump has threatened not to protect Nato members who do not spend enough on defence and promised to cut a quick deal with Russian President Vladimir Putin to put an end to the war in Ukraine.
"I'm not worried. I know both candidates very well. I worked for four years with Donald Trump. He was the one pushing us to spend more, and he achieved," Rutte said.
"I will be able to work with both, whatever is the outcome of the elections."
In opting for the veteran Dutch statesman, a staunch US ally and stalwart backer of Ukraine, Natos 32 nations have picked a leader who will keep pushing support for Kyiv and efforts to bolster the alliance's own defences in the face of Russia.
"Nato will be in safe hands with you at the helm," said Stoltenberg, who has guided the alliance through one of its most tumultuous decades.
Rutte listed backing Kyiv as among his top priorities -- along with ensuring Nato keeps on spending more on defence and bolstering ties with partners, including the European Union and those in the Asia Pacific.
"Putin has to realise that we will not give in, that we want Ukraine to prevail in the end," Rutte warned, saying he wanted "to step up our support for Ukraine and bring it ever closer to Nato."
"We must sustain this support into the future, because Ukraine's rightful place is in Nato," he added.
Ukraine's President Volodymyr Zelensky pledged to work productively with Rutte as his country "continues on its path towards full-fledged NATO membership."
But Kyiv is facing a difficult moment as Russian forces are advancing on the battlefield more than three-and-a-half years after the Kremlin's all-out invasion.
And there is uncertainty over future Western support for Ukraine and growing calls for a resolution to the conflict.
"It's up to the Ukrainian government to decide when they are at a stage that they want to discuss peace," Rutte said. "That's for later."
Rutte backed Ukraine's right to use Western supplied weapons inside Russia, but said it was up to each Nato ally to decide on any limitations.