NATO chief Jens Stoltenberg has hit back against “any suggestion” countries within the alliance would not defend one another after former US President Donald Trump said he would not abide by the collective defense clause at the heart of the alliance if reelected.

In what would be a stunning abandonment of a decades-long core US commitment, Trump, who is running for re-election in November, said during a campaign event Saturday he would encourage Russia to do “whatever the hell they want” to any NATO member country that doesn’t meet spending guidelines and would not offer such a country US protection.

In a statement Sunday, Stoltenberg said such comments put European and American soldiers at an 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,” Stoltenberg said.

“I expect that regardless of who wins the presidential election the US will remain a strong and committed NATO Ally,” he said, while also stressing that any attack on a NATO country would be “met with a united and forceful response.”

Trump’s comments — which come amid an on-going war in Europe and rising concerns about Chinese activity in the South China Sea and toward Taiwan — will likely raise fresh questions among allies in Europe and Asia over the strength of US commitments.

During his time in office, Trump repeatedly railed against spending disparities within NATO and accused some countries of not meeting their obligations. He also criticized American defense pacts with Asian allies Japan and South Korea.

But the latest comments – the most direct indication he does not intend to defend NATO allies from Russian attack if he is elected – land at a time of starkly different circumstances compared to his time in office.

NATO is now heavily involved in supporting Ukraine’s defense following Russia’s 2022 full-scale invasion, which has sparked a mass humanitarian crisis, plunged Europe into its largest conflict since the Second World War and seen Russian leader Vladimir Putin accused of war crimes by the International Criminal Court.

The US and its allies have supported Ukraine with crucial weaponry, training and economic support, though they have not sent troops to Ukraine, which is not a NATO member. The conflict has raised concerns Putin may have further expansionist ambitions, which the leader denies, or that a NATO country may become directly embroiled.

Russia’s invasion of its neighbor prompted Sweden and Finland to seek NATO membership and the collective protection it affords. Finland joined NATO in April 2023, doubling the alliance’s border with Russia. Sweden has faced numerous delays in its path to accession, notably from Turkey but has since made progress towards joining.

The NATO bloc has also moved to deepen collaboration with countries in the Indo-Pacific amid concerns about an increasingly assertive China. Separately, Washington has strengthened coordination with Japan and Korea, which are also warily monitoring ramped-up aggression from North Korea.

Japan, South Korea and the Philippines are all treaty allies with the United States in partnerships that date back decades and have been crucial to Washington’s military influence in the Pacific since the end of the Second World War.

The White House on Saturday slammed Trump’s comments as “appalling and unhinged” and contrasted them with President Joe Biden’s efforts to bolster American alliances for its national security.

‘Reckless’

Several European leaders have condemned Trump’s comments.

The European Union’s foreign policy chief Josep Borrell said Monday that “NATO cannot be an ‘a la carte’ military alliance… depending on the humor of the president of the US.”

European Council President Charles Michel said in a post on X, “Reckless statements on NATO’s security and Art 5 solidarity serve only Putin’s interest. They do not bring more security or peace to the world,” referring to the collective defense clause.

Meanwhile, Polish Prime Minister Donald Tusk said “there is no alternative to the EU, transatlantic cooperation and NATO.”

“The words that illustrate the idea of solidarity - ‘One for all, all for one’ - are the basis of the philosophy of modern Europe and the most important value of contemporary Poland. This requires determined actions for the European community, especially in the context of threats,” Tusk said Monday.

Estonian Prime Minister Kaja Kallas told reporters on Monday that Trump’s comments are “something to maybe wake up some of the allies who haven’t done that much.”

Although disagreeing with some of Trump’s rhetoric, a NATO military official told CNN the former president was “not completely wrong” to suggest certain alliance members should increase their defense spending.

“How is it possible that Europeans are so wealthy and still not capable to solve problems on their own?” the official said. “I am sure many in the alliance see it like this, but it’s of course cheaper to rely on the US.”

The official said they were not speaking for the alliance but stressed that others shared their view.

First created to provide European and North American nations collective security against the Soviet Union, the North Atlantic Treaty Organization now includes 31 countries throughout the wider region.

Enshrined in Article 5 of the treaty is the promise of collective defense — that an attack on one member nation is an attack on all the nations in the alliance.

Trump has for years inaccurately described how the bloc’s funding works.

NATO has a target that each member country spends a minimum of 2% of gross domestic product on defense, and most countries are not meeting that target. But the figure is a guideline and not a binding contract. Member countries haven’t been failing to pay their share of NATO’s common budget to run the organization.

As of 2022, seven countries were meeting the 2% target, up from three in 2014, with European allies and Canada increasing spending for eight consecutive years, according to NATO.

At the Saturday event, Trump claimed “one of the presidents of a big country” at one point asked him whether the US would still defend the country if they were invaded by Russia even if they “don’t pay.”

“No, I would not protect you,” Trump claimed to recall telling that president. “In fact, I would encourage them to do whatever the hell they want. You got to pay. You got to pay your bills.”

Biden said Sunday that Trump “is making it clear that he will abandon our NATO allies” and outlined the potential consequences of Trump’s comments.

“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 via his campaign.

In the wake of Russia’s full-scale invasion of Ukraine, the US leader has repeatedly said NATO is more united than ever before. Even prior to the war, he sought to bolster and repair American alliances following the Trump-era years of “America First.”

Trump’s comments also come as US lawmakers are deciding the direction of US support for Ukraine. The US Senate on Sunday took a step closer to passing a $95.3 billion foreign aid bill with crucial assistance for Ukraine and Israel following a key vote to move the package forward.