US President Donald Trump has urged the United Kingdom not to transfer the Chagos Islands to Mauritius, warning that it could weaken British control over the strategically important Diego Garcia military base.

Trump said handing over sovereignty of the islands would be a serious mistake, especially if the UK only keeps Diego Garcia through a long-term lease agreement. He strongly criticised the idea of Britain giving up direct authority over the territory, calling it risky for Western security.

Trump shared his views in a long post on his social media platform Truth Social. In the post, he said he has been personally pushing UK Prime Minister Keir Starmer to reconsider the agreement.

“I have been telling Prime Minister Keir Starmer that Leases are no good when it comes to Countries,” Trump wrote. He also described the proposed lease as “tenuous, at best,” suggesting it would not provide strong enough protection for such an important defence location.

His comments came just one day after the US State Department said that Washington supports the UK’s decision to go ahead with the agreement with Mauritius. This showed a clear difference between Trump’s personal position and the current official stance of the US government.

According to the agreement reached in 2025, the UK plans to transfer sovereignty of the Chagos Islands to Mauritius. However, Britain would still retain access to Diego Garcia, which is home to a joint US-UK military base. The base would continue operating under a 99-year lease, allowing the UK and the US to keep using it for defence purposes.

Diego Garcia is located in the Indian Ocean and is considered one of the most important military sites in the region. It has long served as a key American air base and has been used for major US military operations in the Middle East and parts of Asia. Because of its location, the base plays an important role in global security and military planning.

Trump argued that if Britain gives up sovereignty, it could lose control over a critical security asset. He claimed that even with a lease in place, Britain’s grip on the island would be weaker than before.

“Prime Minister Starmer is losing control of this important Island,” Trump wrote. He also dismissed the competing claims over the territory, calling them fictitious in nature. Trump suggested that the UK has a strong historical and strategic reason to keep control of the land.

Trump also connected the issue to rising global tensions, especially with Iran. He warned that if diplomatic talks fail, the US may need to rely on Diego Garcia for military action.

“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,” Trump wrote.

He said the base could become crucial in case of any threat from Iran, and any move that weakens authority over Diego Garcia could create risks. Trump added that such a decision could affect not only Britain but also other friendly countries that depend on Western military strength and stability.

Trump warned that giving up sovereignty could lead to uncertainty in the future, even if a lease lasts for many decades. He argued that leases do not provide the same security as full ownership and control of territory.

“This land should not be taken away from the UK,” he said. Trump ended his statement with a strong message in capital letters: “DO NOT GIVE AWAY DIEGO GARCIA!”

While Trump’s remarks appear to challenge the current agreement, he still stressed that the relationship between the US and the UK remains strong. He described the alliance as “strong and powerful,” and said the United States would always support Britain.

Trump said the US is ready to stand by the UK whenever needed, showing that his criticism of the deal does not mean he is against the partnership. Instead, he believes the UK should hold on to Diego Garcia because of its long-term strategic value.

His comments have now brought renewed attention to the Chagos Islands issue, which remains sensitive due to history, international claims, and global security interests.