Former US President Donald Trump said on Saturday that he would "encourage" Russia to attack members of NATO who had not met their financial obligations, in remarks that the White House rejected as "appalling and unhinged."

Speaking at a campaign rally in South Carolina Saturday, the Republican presidential nomination frontrunner appeared to recount a conversation with a fellow head of state at an unspecified NATO meeting.

"One of the presidents of a big country stood up and said, 'Well, sir, if we don't pay, and we're attacked by Russia, will you protect us?' I said, 'You didn't pay, you're delinquent?'"

"No, I would not protect you. In fact, I would encourage them to do whatever the hell they want. You got to pay. You got to pay your bills."

The NATO treaty contains a provision that assures mutual defense of member states if one is attacked, but it also stipulates that members should spend 2% of their GDP on defense, a target that the majority of states regularly fail to meet. 

Biden labels Trump's remarks 'appalling and dangerous'

Trump has long expressed skepticism about the 31-nation military alliance.

On being asked about Trump's statement White House spokesperson Andrew Bates, said: "Encouraging invasions of our closest allies by murderous regimes is appalling and unhinged — and it endangers American national security, global stability and our economy at home."

US President Joe Biden criticized "appalling and dangerous" comments by Trump. Biden said Sunday that the former president seeks to give Russian leader Vladimir Putin "a greenlight for more war and violence."

"Donald Trump's admission that he intends to give Putin a greenlight for more war and violence, to continue his brutal assault against a free Ukraine, and to expand his aggression to the people of Poland and the Baltic States are appalling and dangerous," Biden said in a statement.

European Council President Charles Michel also denounced Trump's comments as "reckless."

"The Transatlantic Alliance has underpinned the security and the prosperity of Americans, Canadians and Europeans for 75 years," said Michel on X, formerly Twitter." Reckless statements on #NATO's security and Art 5 (Article 5) solidarity serve only Putin’s interest."

Article 5 of the  949 North Atlantic Treaty says that if a NATO Ally is attacked, each member of the Alliance will consider this an attack against all members and will take the actions it deems necessary to assist the ally under threat.

NATO chief Jens Stoltenberg, meanwhile, warned in a statement that, "Any suggestion that allies will not defend each other undermines all of our security, including that of the US."

"Any attack on NATO will be met with a united and forceful response," he added.

Trump looks set to run again as the Republican candidate for the White House in this year's presidential election.

Trump's comments came after Senate Republicans on Wednesday rejected a bipartisan bill that would have included crucially needed new funding for Ukraine, and aid for ally Israel, along with reforms to deal with the US-Mexico border crisis.

The Senate bill's death highlighted Trump's tight hold on the Republican Party, as its lawmakers acceded to the former president's calls to shoot down any deal in order to deny Biden a win on immigration ahead of November's election.

Trump's relationship with NATO

In his 2016 presidential campaign, Trump shocked Western allies by cautioning that under his leadership the US might abandon its NATO treaty commitments and only come to the defense of those nations that meet the bloc's military funding guidelines.

During his presidency, Trump eventually endorsed NATO's Article 5 mutual defense clause, which says that an armed attack against one or more of its members shall be considered an attack against all members.

But he often portrayed NATO allies as leeches on the American military and cast aspersions on the value of the military alliance that has been a cornerstone for US foreign policy for decades.

As Trump leads President Joe Biden in some polls, European allies are concerned that the US commitment to the alliance could be in jeopardy if Trump wins the November electoral race. 

However, NATO Secretary General Jens Stoltenberg said in January that he did not think a second Trump presidency would threaten US membership.

dvv/ab (AFP, AP, Reuters)