President Donald Trump made an about-face on Britain's plans to hand over the Diego Garcia atoll to the nation of Mauritius, calling the move "an act of total weakness." He had previously endorsed the deal, but now says it's just another reason Washington must take control of Greenland.

Trump took to his Truth Social account to blast the UK's Diego Garcia agreement early on Tuesday morning, insisting the decision would only benefit Moscow and Beijing.

"Shockingly, our 'brilliant' NATO Ally, the United Kingdom, is currently planning to give away the Island of Diego Garcia, the site of a vital US Military Base, to Mauritius, and to do so FOR NO REASON WHATSOEVER," he said. "There is no doubt that China and Russia have noticed this act of total weakness."

"The UK giving away extremely important land is an act of GREAT STUPIDITY, and is another in a very long line of National Security reasons why Greenland has to be acquired. Denmark and its European Allies have to DO THE RIGHT THING," the president added.

The comments marked a major U-turn from last May, when the Trump administration explicitly endorsed the deal with Mauritius, calling it a "historic agreement" that would secure "the long-term, stable, and effective operation of the joint US-UK military facility at Diego Garcia."

"We commend both the United Kingdom and Mauritius for their leadership, vision, and commitment to ensure that Diego Garcia remains fully operational for the duration of this agreement," Secretary of State Marco Rubio said at the time.

Part of the remote Chagos Archipelago in the Indian Ocean, Diego Garcia came under British control in 1814 following the Napoleonic Wars, but was administered from Mauritius until 1965. That year, the UK purchased the atoll for £3 million, and soon after struck a deal with Washington to allow for a US troop presence there.

As part of the island's militarization, UK forces opted to expel its native inhabitants beginning in 1968, completing the task by the early 1970s.

After the the International Court of Justice issued a non-binding ruling in 2019 which called on the UK to cede control of the territory, London worked to reach an agreement with Mauritius, ultimately announcing a deal last year. Though the agreement still must be ratified by the UK parliament, it would allow the US and UK to retain control of their joint military base through a 99-year lease.