BRUSSELS - The US commitment to NATO will remain "unwavering" despite the change to the adminstration of President-elect Donald Trump, outgoing US Secretary of State John Kerry said Tuesday.

"The change of the administration will not change the unwavering commitment of the US to... our NATO obligations," Kerry said after talks with his NATO counterparts in Brussels. "The US commitment to NATO and Article Five transcends politics," added Kerry, referring to the military alliance's collective defence policy in which an attack on one member is an attack on all.

Trump stoked concerns that Washington's near 70-year European defence guarantee might no longer hold when he said on the campaign trail he would think twice about helping NATO allies who did not pay their defence dues.

His commitments particularly alarmed eastern European NATO countries that are on edge about a more assertive Moscow following Russia's annexation of Crimea and involvement in the conflict in Ukraine.

But Kerry insisted that both the Trump administration and the US Congress would continue to back NATO.

"I'm absolutely confident that the next administration and congress will stand together," Kerry said in his swansong to Europe.