The US could review Britain’s claim to the Falkland Islands as punishment for a lack of support in Donald Trump’s war on Iran.

A leaked internal Pentagon email suggested a review of Washington’s position on Britain’s claim to the islands, as US officials outlined options to punish Nato allies for their response to the outbreak of conflict in the Middle East.

The confidential memo, which also considers suspending Spain from the alliance, expresses frustration over certain allies’ reluctance or refusal to support Washington’s military action on Tehran.

The US president has hit out repeatedly at Nato since he launched his offensive, branding the alliance a “paper tiger” and threatening to withdraw altogether.

He has also repeatedly attacked Britain and Sir Keir Starmer, branding him “no Winston Churchill” after he initially did not grant a request from the US to attack Iran from British bases.

An official, speaking anonymously to Reuters, said that Access, Basing, and Overflight (ABO) is “just the absolute baseline for Nato,” adding that these options are circulating at high levels within the Pentagon.

The leaked memo laid bare the tense relations between Britain and the Trump administration, as it includes an option to reassess US diplomatic support for longstanding European “imperial possessions,” such as the Falkland Islands.

The State Department’s website states that the islands are administered by the UK but are still claimed by Argentina, whose libertarian president Javier Milei is a Trump ally.

Britain and Argentina fought a brief war in 1982 over the islands after Argentina made a failed bid to take them. Some 650 Argentine soldiers and 255 British troops died before Argentina surrendered.

Pentagon press secretary Kingsley Wilson said the US War Department will ensure Mr Trump “has credible options to ensure that our allies are no longer a paper tiger and instead do their part”.

“As President Trump has said, despite everything that the United States has done for our Nato allies, they were not there for us,” she said.

Mr Trump has also openly considered withdrawing from Nato, asking, “wouldn’t you if you were me?” when questioned about the possibility of a US pull-out earlier this month.

Further proposals within the Pentagon email envision the suspension of “difficult” countries from important or prestigious positions within the Nato framework.

But, the official said the memo does not suggest that the US leaves the alliance, and it does not propose closing bases in Europe.

The official declined to say whether the options included a widely expected US drawdown of some forces from Europe, however.

Mr Trump’s war on Tehran has raised serious questions about the future of ​the 76-year-old bloc, after Britain, France and others refused to join offensive attacks or the US naval blockade on the Strait of Hormuz.

He has accused Nato members of “not being there” for the US in times of conflict, and criticised them for failing to deploy their navies to help secure the Strait of Hormuz.

The memo also expressed frustration with Spain, where the Socialist leadership said it ​would not allow its bases or airspace to be used to attack Iran.

The official did not disclose how the United States might pursue suspending Spain from the alliance, and Reuters could not immediately determine whether there was an existing mechanism at Nato to do so.

The option to suspend Spain from the alliance would have a limited effect on US military operations but a significant symbolic impact, the email argues.

Addressing reporters at the Pentagon earlier this month, Defense Secretary Pete Hegseth said “a lot has been laid bare” by the war with Iran, noting that Iran’s longer-range missiles cannot hit the United States but can reach Europe.

“We get questions, or roadblocks, or hesitations … You don’t have much of an alliance if you have countries that are not willing to stand with you when you need them,” Hegseth said.