Sovereignty of the Falkland Islands rests with the UK, Downing Street has said, following a report the US could review its position on Britain's claim to the territory.
An internal Pentagon email reported by Reuters suggested the US was considering options to punish NATO allies it believed had failed to support its war on Iran.
The options discussed also included seeking Spain's suspension from NATO over its opposition to the war. BBC News has not been able to review the email.
A Pentagon spokesperson did not comment on the email's existence, but said it would ensure that the president has credible options to ensure that our allies are no longer a paper tiger and instead do their part.
As President [Donald] Trump has said, despite everything that the United States has done for our NATO allies, they were not there for us, the spokesperson added.
The Falkland Islands, a British overseas territory in the south-west Atlantic Ocean, remain the subject of a sovereignty dispute between Britain and Argentina.
Asked about the report, a No 10 spokesman on Friday said: The Falkland Islands have previously voted overwhelmingly in favour of remaining a UK overseas territory, and we've always stood behind the islanders' right to self-determination and the fact that sovereignty rests with the UK.
The prime minister's official spokesman also said the government could not be clearer about the UK's position, and that sovereignty rests with the UK and the islanders' right to self-determination is paramount.
He continued: We've expressed this position previously clearly and consistently to successive US administrations and nothing is going to change that.
Former Labour security minister Lord West, on BBC Radio 4's The World Tonight programme, described the Pentagon leak on the Falklands as quite extraordinary and showed a lack of understanding.
Lord West, who was an officer commanding HMS Ardent during the Falklands War, went on to describe US Defence Secretary Pete Hegseth as thick and accused him of having a total lack of understanding about NATO.
Under NATO's Article 5, an armed attack against one or more members is considered an attack against all, and in response each other member would take such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.
The only time Article 5 has been invoked was after the 9/11 attacks on the US in 2001.
Previous US administrations have formally recognised the UK's de facto administration of the islands, but have not taken a formal position regarding sovereignty.
The Falkland Islands has complete confidence in the commitment made by the UK government to uphold and defend our right of self-determination, the islands' government said in a statement.
Conservative leader Kemi Badenoch said the reported US stance on the Falkland Islands was absolute nonsense, adding: We need to make sure that we back the Falklands. They are British territory.
Reform UK's Nigel Farage stated, This is utterly non-negotiable. There is no way we're even going to have a debate about the sovereignty of the Falkland Islands. He also mentioned raising the issue with Argentina's President Javier Milei when he meets him later this year.
While the White House is yet to comment on the report, it could prove to be another point of friction between the US and UK at a time of diplomatic tension.
Trump has previously said he is not happy with the level of support offered by the UK during its war in Iran, while Sir Keir Starmer has repeatedly said Britain will not be drawn into a wider conflict.
The report emerged three days before King Charles III and Queen Camilla are due to travel to the US and meet Trump at the White House.
Argentina's foreign minister Pablo Quirno rejected the UK stance, asserting Argentina's sovereign rights over the Malvinas Islands and expressing a willingness to engage in bilateral negotiations with the UK to find a peaceful resolution to the sovereignty dispute.
