The US president has lashed out at European partners for declining to contribute military forces to the war on Iran.

United States President Donald Trump has reportedly discussed withdrawing from NATO, the transatlantic alliance that has been a central pillar of Western security for decades.

At a news briefing on Wednesday, White House Press Secretary Karoline Leavitt framed the US and Israel’s war on Iran as a “test” that the alliance had failed.

Despite Trump’s pressure, NATO allies had declined to contribute military forces to the war, outside of defensive manoeuvres.

Leavitt’s comments came shortly before Trump met with NATO Secretary-General Mark Rutte at the White House.

“I have a direct quote from the president of the United States on NATO, and I will share it with all of you. They were tested, and they failed,” Leavitt said.

“I would add, it’s quite sad that NATO turned their backs on the American people over the course of the last six weeks, when it’s the American people who have been funding their defence.”

Trump, she continued, was preparing to have “a very frank and candid conversation” with Rutte that afternoon.

The US president has had a mixed relationship with NATO, sometimes threatening to pull US support and, at other times, reassuring allies of the US’s continued commitment to the alliance.

Since returning to the presidency in 2025, Trump has renewed his pressure campaign for NATO’s European partners to step up their defence spending.

Last June, at the 2025 NATO summit, he largely succeeded. The NATO members agreed to nonbinding commitments to increase their defence budgets to 5 percent of their gross domestic product (GDP) by 2035.

But Spain sought an exemption, leading Trump to denounce the country repeatedly over the past year.

Tensions between the US and its European allies were further strained last year when Trump threatened to use military force to seize the self-governing Danish territory of Greenland, claiming that its ownership was essential for national security.

The US has eased away from those threats. But Trump has continued to assert that US ownership of Greenland is necessary, despite strong protests from the territory’s residents and European leaders.

After the US and Israel unilaterally launched a war against Iran on February 28, Trump lashed out at European countries for their lack of interest in contributing to the campaign.

Many legal scholars consider the war an act of aggression, in violation of international law.

The Wall Street Journal reported on Wednesday that the Trump administration is considering whether to close US bases or move troops out of countries such as Spain and Germany as punishment for their stance on the war.

When asked by reporters if Trump was considering leaving NATO, Leavitt said it was something the president “has discussed” and could address after his meeting with Rutte.

Trump and Rutte are considered to have a close relationship. Rutte has visited the White House multiple times during Trump’s second term, including in March, July, August and October of last year.

In the past, Rutte has warned that NATO “will not work” without US support.