Why is Trump attacking the UK over Diego Garcia again? US President's fresh attack on Chagos deal explained

US President Donald Trump has reopened a diplomatic fault line between Washington and London, urging Britain not to proceed with its plan to hand sovereignty of the Chagos Islands to Mauritius and lease back Diego Garcia, the strategically vital military base used by US and British forces.

In a sharply worded social media post on Wednesday, the US president warned that leasing arrangements were “no good when it comes to Countries” and suggested the agreement could weaken Britain’s control over a key Indo-Pacific outpost at a moment of heightened tensions with Iran.

The intervention comes despite the US State Department having formally endorsed the UK-Mauritius agreement only a day earlier, underscoring the erratic messaging that has come to define Trump’s foreign policy.

Why Donald Trump said: “Do not give away Diego Garcia”

Trump framed the planned handover as a strategic error and a political embarrassment for the United Kingdom, casting it as an unnecessary concession that could undermine a close ally.

“Do not give away Diego Garcia,” he wrote, criticising the UK’s plan to cede sovereignty and lease back the base.

He added that “this land should not be taken away from the UK” and warned that if it were, it would be “a blight on our Great Ally”.

The post, published on Truth Social, was explicitly directed at Prime Minister Keir Starmer, with Trump arguing that Britain would lose leverage by accepting a long lease rather than retaining full sovereignty.

“I have been telling Prime Minister Keir Starmer, of the United Kingdom, that Leases are no good when it comes to Countries, and that he is making a big mistake by entering a 100 Year Lease...” Trump wrote.

Why Diego Garcia matters to the US and UK

Diego Garcia, the largest island in the Chagos archipelago, hosts one of the most important military facilities in the Indian Ocean. It is operated as a joint base by the US and UK armed forces and is widely regarded as a linchpin for operations spanning the Middle East, East Africa and the Indo-Pacific.

Trump emphasised the base’s geography, describing it as “strategically located in the Indian Ocean”.

He claimed Starmer was “losing control of this important Island by claims of entities never known of before,” a reference to Mauritius’s long-standing legal and diplomatic challenge to British sovereignty.

Trump also tied Diego Garcia to potential military escalation with Iran, invoking ongoing talks over Tehran’s nuclear programme.

“Should Iran decide not to make a Deal, it may be necessary for the United States to use Diego Garcia... in order to eradicate a potential attack by a highly unstable and dangerous Regime,” he wrote.

The Republican president has repeatedly threatened military action against Iran over its nuclear activities and its crackdown on protests. The US and European allies suspect Iran is moving towards the development of a nuclear weapon, something Tehran has always denied.

The UK’s deal with Mauritius: 99-year leaseback and sovereignty transfer

The agreement at the centre of Trump’s criticism was announced last May. Under its terms, the UK would cede sovereignty of the British Indian Ocean Territory — commonly known as the Chagos Islands — to Mauritius, while leasing back Diego Garcia for 99 years.

Starmer has previously argued the deal is essential to protect the base’s continued operation, particularly given repeated legal challenges to British control of the islands.

The Chagos Islands have been under British control since 1814 and were established as an overseas territory in 1965. Mauritius, however, has long argued it was illegally forced to relinquish the islands as part of the conditions for independence.

In the late 1960s, Britain invited the United States to build a military base on Diego Garcia, forcibly removing thousands of Chagossians from their homes in the process. Many were resettled in Mauritius and the Seychelles, while others later moved to the UK, particularly to Crawley in West Sussex.

US policy whiplash: State Department backed the deal a day earlier

Trump’s intervention is politically awkward for Starmer, not only because it comes from Washington, but because it contradicts the official US position expressed earlier this week.

On Tuesday, the US Department of State said it “supports the decision of the United Kingdom to proceed with its agreement with Mauritius concerning the Chagos archipelago”.

That endorsement was meant to remove doubts about whether the US military would remain secure under the leaseback arrangement. Trump’s post has instead revived questions about whether the White House and State Department are aligned.

Asked about the president’s remarks, White House press secretary Karoline Leavitt said the post should be treated as official policy.

“The post should be taken as the policy of the Trump administration, it's coming straight from the horse's mouth. When you see it on Truth Social you know it's directly from President Trump, that's the beauty of this president in his transparency and relaying this administration's policies.”

The UK response: “crucial to the security of the UK and our key allies”

Britain moved quickly to defend the agreement, framing it as a security measure rather than a diplomatic retreat.

In response to Trump, the Foreign Office said the Chagos deal was “crucial to the security of the UK and our key allies, and to keeping the British people safe”.

“The agreement we have reached is the only way to guarantee the long-term future of this vital military base,” it said.

Officials have argued that a negotiated settlement is preferable to prolonged legal uncertainty, which could jeopardise the base’s operations.

Trump’s deeper objection: sovereignty, not logistics

Trump’s critique is not simply about the lease term. It is rooted in his broader view that long leases signal weakness and invite future disputes — a worldview shaped by his background in property development and his preference for maximal leverage in negotiations.

The US President argued that Britain was making a mistake by giving up sovereignty and relying on a lease to secure continued access. He also framed the issue through the lens of culture-war politics.

“We will always be ready, willing, and able to fight for the UK, but they have to remain strong in the face of Wokeism, and other problems put before them,” he wrote.

The language signalled that Trump sees the dispute not only as a matter of strategy, but also as part of his broader critique of liberal governance in allied capitals.

UK politics: Starmer accused of weakness as rivals seize on Trump attack

The US president’s post immediately triggered a new wave of domestic criticism, with opposition parties portraying it as proof that the UK’s approach had backfired.

Shadow foreign secretary Priti Patel described the remarks as “an utter humiliation” for Starmer.

“It's time Starmer finally saw sense, U-turned and scrapped this appalling deal altogether,” she said.

Liberal Democrat leader Ed Davey argued the episode showed the UK could not depend on Washington while Trump remained in office.

“Trump's endless flip-flopping on the Chagos Islands shows why Starmer's approach is doomed to fail,” he wrote on X.

“Britain can't rely on the US while Trump is in the White House. It's time to strengthen our ties with allies we can depend on, starting with our neighbours in Europe.”

Reform UK leader Nigel Farage, a long-time critic of the handover, welcomed Trump’s intervention.

“Keir Starmer risks alienating our most important ally by giving away the Chagos Islands, the worst deal in British history,” he wrote on X.

“President Trump is right to say the Prime Minister is making a big mistake. Starmer must cancel this deal.”

Chagossian protest intensifies as deal faces mounting scrutiny

The political dispute is unfolding alongside renewed protests from Chagossians themselves. Earlier this week, four Chagos islanders opposing the handover landed on the remote atoll as part of a protest. They refused to leave, despite the threat of eviction by a British maritime patrol.

The protest reflects a long-standing grievance: that Chagossians were displaced to enable the US base, and that decisions about sovereignty are being made without their consent.

What happens next: US-Mauritius talks and growing uncertainty

Trump’s comments come ahead of talks between the United States and Mauritius planned for next week, increasing the risk that the dispute will spill into formal diplomacy.

The US president’s stance has also shifted repeatedly in recent months, swinging from calling the transfer an “act of great stupidity” to suggesting it was the “best” deal Starmer could make — and now returning to outright opposition.

For Britain, the immediate challenge is to keep the agreement on track while reassuring Washington that the base will remain secure. For the United States, the deeper question is whether the administration’s official policy is determined by the State Department — or by the president’s latest post.