Trump sowing doubts about US commitment to Nato is 'un-American': Biden

President Joe Biden on Tuesday said Donald Trump's comments calling into question the US commitment to defend its Nato allies from attack were "dangerous" and "un-American", seizing on the former president's comments that sowed fresh fears among US partners about its dependability on the global stage.

Trump, the frontrunner in the US for the Republican Party's nomination this year, said on Saturday that he once warned that he would allow Russia to do whatever it wants to Nato member nations that are "delinquent" in devoting two per cent of their gross domestic product to defence. It was the latest instance in which the former president seemed to side with an authoritarian state over America's democratic allies.

Speaking from the White House as he encouraged the House to take up a Senate-passed aid bill to fund Ukraine's efforts to hold off a two-year Russian invasion, Biden said Trump's comments about the mutual defence pact were "dangerous and shocking".

"The whole world heard it and the worst thing is he means it," Biden added.

Biden said that "when America gives its word, it means something", and called Trump's comments sowing doubt about its commitments "un-American".

Biden said of Trump, "He doesn't understand that the sacred commitment that we've given works for us as well.