Trump Attacks Chagos Deal Starmer’s Strategic Crisis in 2026

Only a day ago, Sir Keir Starmer’s was urging calm discussion with Washington. By morning, he was confronting a US president in full political spin cycle, unpredictable, theatrical, and firing off grievances in every direction.

One of those directions is Britain, and directly at the prime minister himself.

Starmer’s Strategic Crisis in 2026

This moment presents Sir Keir with a stark strategic dilemma, perhaps the most serious of his premiership so far. How does he respond now?

Since entering office, Starmer has invested heavily in cultivating a close relationship with Donald Trump, shaping his foreign policy around the idea of being a dependable, discreet ally who avoids public confrontation. Amid a difficult domestic start for the government, that relationship was widely viewed as an unexpected success.

Trump spoke warmly of the prime minister, and Downing Street believed it enjoyed a stronger line into the White House than many European capitals, an advantage it saw as paying dividends. The tariff agreement reached with the US last year was held up internally as proof that this approach worked.

Now, that confidence has been shaken. First Greenland, now the Chagos Islands.

The government is defending its agreement to transfer sovereignty of the Chagos Islands to Mauritius, announced last year, after Trump erupted on social media over the deal. Senior officials insist the decision was taken for compelling strategic and legal reasons, and note that it was publicly welcomed at the time by both the United States and Australia, alongside the UK in the Five Eyes intelligence alliance.

Ministers have long argued that unresolved legal challenges to Britain’s claim over the Chagos archipelago threatened the future of the joint US UK military base on Diego Garcia, a facility regarded as critical by both London and Washington. The agreement with Mauritius, they say, secures the base for the long term.

That explanation, however, now clashes with Trump’s dramatic change of tone.

When the president was first asked publicly about the Chagos deal nearly a year ago, he sounded supportive. I was in the Oval Office at the time. Reporters expected scepticism, but it did not come. When the agreement was formally concluded last May, Washington welcomed it again.

Now, Trump has reversed course, unleashing a barrage of capitalised outrage online. It may not stop there.

The UK government has also recently approved plans for a new Chinese embassy in London, a long standing ambition for Beijing and a decision that critics warn could carry security risks. There are known concerns in Washington about any perception that Britain is growing closer to China.

With the prime minister expected to visit China in the coming weeks, the timing raises an uncomfortable question. Could the embassy decision be the next trigger for presidential fury? Right now, it feels entirely plausible.

Trump has explicitly linked Britain’s Chagos decision to his argument for acquiring Greenland. Posting on Truth Social, he accused the UK of planning to give away Diego Garcia, home to what he described as a vital US military base, “for no reason whatsoever”.

He claimed that China and Russia would see the move as weakness, and argued that Britain’s actions were “another in a very long line of national security reasons why Greenland has to be acquired”.

The comments will have stunned Downing Street, particularly after the US secretary of state, Marco Rubio, gave a warm endorsement of the deal when it was first agreed.

A UK government spokesperson said Britain would never compromise on national security, stressing that court rulings had undermined the UK’s legal position and risked the base’s future operations.

“This deal secures the operations of the joint US UK base on Diego Garcia for generations,” the spokesperson said, adding that it had been welcomed by the US, Australia and other Five Eyes partners, as well as countries including India, Japan and South Korea.

Trump’s intervention has reignited fierce domestic criticism. The shadow foreign secretary, Priti Patel, said the president had confirmed what the opposition had long argued, that the deal was bad for Britain and its security.

Conservative leader Kemi Badenoch went further, calling the handover an act of self sabotage that weakened Britain and its Nato allies. She said she had discussed the issue with Mike Johnson, who she claimed shared her concerns.

Nigel Farage welcomed Trump’s stance, while Andrew Rosindell, who recently defected from the Conservatives to Reform UK, cited the Chagos issue as a key reason for leaving his party.

Inside government, ministers are playing down the impact. Darren Jones, the chief secretary to the Treasury, said the deal with Mauritius had been signed, legislated for and agreed, and that it secured the base for the next century.

He also argued that Starmer’s calm approach to Trump, including over threatened tariffs linked to Greenland, remained the right one. British diplomacy, he said, was working, even if the noise was unprecedented.

Read More: Newsom Accuses Europe of ‘Pathetic’ Complicity on Greenland 2026

Under the agreement, Britain cedes sovereignty of the Chagos Islands to Mauritius but leases Diego Garcia for 99 years to continue operating the joint base. In 2021, a UN court issued an advisory opinion that the UK did not have rightful sovereignty over the archipelago, a ruling ministers say left them little choice.

When the deal was announced in May 2025, Rubio said the US welcomed the agreement, calling Diego Garcia a critical asset for global security and describing the deal as a reflection of the enduring strength of the US UK relationship.

Critics argue the handover could create space for Chinese influence, given Mauritius’s close ties with Beijing, a concern Trump frequently cites when justifying his Greenland ambitions.

Starmer is not expected to attend Davos, where Trump will be speaking, although the US president has posted what appeared to be a message from Emmanuel Macron urging him to convene talks there on the Greenland crisis.

For the prime minister, the question now is whether his carefully cultivated strategy of quiet diplomacy can survive a White House that is no longer playing by familiar rules.