BRUSSELS (AFP) - Nato head Jens Stoltenberg on Tuesday (Nov 15) said he was sure that Donald Trump would meet all US commitments to the alliance, just days after urging the President-elect not to go it alone.

"President-elect Donald Trump stated during the election campaign that he is a big fan of Nato," Stoltenberg said in Brussels as he arrived for talks with EU defence ministers.

"And I am certain that he will be a president... who will live up to all the commitments of the United States in the alliance, because a strong Nato is important for Europe but it's also important for the United States."

Trump's upset election badly rattled nerves in Europe after he appeared to call into question Washington's near 70-year security guarantee by saying he would only help Nato allies if they paid their way.

In a stark warning in Britain's Observer newspaper on Sunday, Stoltenberg wrote "going it alone is not an option... this is no time to question the partnership between Europe and the United States".

But the Nato chief noted Tuesday that the two sides were on the same page, with Trump having also called for increased defence spending in Europe.

"I absolutely agree with him; that has been the message from US leaders for many years," Stoltenberg said.

"The good thing is that we now see that Europeans are actually investing more in defence... therefore contributing to better burden sharing," he said.

The Ukraine crisis shook Nato out of years of complacency and defence cuts, with leaders agreeing to its biggest military build-up since the end of the Cold War based on a commitment to devote two per cent of national output to defence.

On Monday, US President Barack Obama said he was sure Trump would stand by US security commitments and that he would tell Europe there would be "no weakening when it comes to America's commitment to maintaining a strong and robust Nato relationship".