NATO head Jens Stoltenberg says Donald’s Trump’s suggestion that the US should not protect allies who fail to spend enough on defence “undermines all of our security”.

Speaking at a rally in South Carolina on Saturday, the former US president said he remembered how as president he told an unidentified Nato member that he would “encourage” Russia to do as it wishes in cases of what he called “delinquent” Nato allies.

The Republican presidential frontrunner said Russia should be able to do "whatever the hell they want" to alliance members who don’t meet their defence spending targets.

“‘You didn’t pay? You’re delinquent?’” Trump recounted saying at his Conway rally.

“‘No, I would not protect you. In fact, I would encourage them to do whatever the hell they want. You gotta pay. You gotta pay your bills.’”

The Nato secretary-general contradicted the comments from Mr Trump, who is seeking to return for a second term as US president, and said that all 31 allies of the Nato bloc were committed to defending each other.

“Nato remains ready and able to defend all allies. Any attack on Nato will be met with a united and forceful response,” he said.

He added Mr Trump’s remarks "put American and European soldiers at increased risk".

“Any suggestion that allies will not defend each other undermines all of our security, including that of the US, and puts American and European soldiers at increased risk,” Mr Stoltenberg said on Sunday.

“Regardless of who wins the presidential election, the US will remain a strong and committed Nato ally,” he said.

Mr Trump said he had informed his allies he would "encourage" Russia to attack any Nato member not meeting the alliance’s agreed defence spending target of 2 per cent of their GDP.

At least 19 of 30 member nations in the Nato bloc are spending less than that, data from Nato showed in 2023.

These nations include Germany, Norway and France.

Mr Trump’s comments triggered a wave of concern in Poland, which is facing increased risk of attack from Russia. The central European nation has been under Russian control more often than not since the end of the 18th century.

Defence minister WÅ‚adysÅ‚aw Kosiniak-Kamysz warned that “no election campaign is an excuse for playing with the security of the alliance”.

While the German government did not officially comment, its foreign office published a statement on Sunday morning highlighting the principle of solidarity governing Nato.

“‘One for all and all for one.’ This Nato creed keeps more than 950 million people safe – from Anchorage to Erzurum," the foreign ministry said on X, formerly Twitter.

Mr Trump’s remarks were also condemned by his successor Joe Biden, who said that his comments would embolden Vladimir Putin and that a second Trump administration could contribute to a widening conflict in Europe.

"Donald Trump’s admission that he intends to give Putin a green light 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, [is] appalling and dangerous," he said.

While in office, Mr Trump had already threatened not to come to the aid of any country under attack that he deemed not to be meeting its Nato commitments.

Trump: NATO nations ‘are at it again’ on funding

Former President Trump doubled down on his criticism of NATO, arguing Monday that the military alliance was more robust under his leadership in the White House.

Trump claimed he made NATO “strong” during his administration by pressing members to pay more to meet the alliance’s defense spending targets. He urged the alliance to “equalize” and do the same thing today.

“I MADE NATO STRONG, and even the RINOS and Radical Left Democrats admit that,” Trump wrote Monday in a post on Truth Social. “When I told the 20 Countries that weren’t paying their fair share that they had to PAY UP, and said without doing that you will not have U.S. Military Protection, the money came rolling in.”

“After so many years of the United States picking up the tab, it was a beautiful sight to see. But now, without me there to say YOU MUST PAY, they are at it again,” he added

The former president’s remarks come in the face of scrutiny from various U.S. and top Western officials after he shared a story at a South Carolina rally over the weekend about how an unidentified foreign leader once questioned him about his threat not to defend members who fail to reach the alliance’s defense spending targets.

He continued, claiming he told the leader he would “encourage” Russia to do whatever it wishes and recounted saying, “You didn’t pay? You’re delinquent.”

During his presidency, Trump repeatedly pressed member nations to commit 2 percent of their GDP to defense spending. NATO Secretary-General Jens Stoltenberg said at least half of the 31-member alliance are expected to meet that figure in 2024, which is up from seven members in 2022.

The former president repeatedly threatened to withdraw from the alliance during his presidency and John Bolton, who served as national security adviser under his administration, warned Trump could try to push forward with his threat if elected to a second term.

Stoltenberg on Sunday said Trump’s remarks put the safety of U.S. troops and their allies at risk.

Trump also pointed to the billions of U.S. dollars spent in funding for Ukraine in his recent push for NATO to be more aggressive in getting members to reach spending targets.

“We are into helping Ukraine for more than 100 Billion Dollars more than NATO,” he wrote. “We have nobody that they respect, and they insist on paying far less than we do. Wrong, NATO HAS TO EQUALIZE, AND NOW. THEY WILL DO THAT IF PROPERLY ASKED. IF NOT, AMERICA FIRST! MAKE AMERICA GREAT AGAIN.”

President Biden called Trump’s weekend remarks “appalling and dangerous,” while Former United Nations Ambassador Nikki Haley — Trump’s main GOP primary challenger — warned the former president should not “take the side of a thug,” referring to Russian President Vladimir Putin.