Donald Trump accused Britain of an “act of total weakness” over the Chagos Islands as he lashed out in the row over his bid to grab Greenland.
In an early morning post, the US president accused the UK of giving away an “extremely important land is an act of GREAT STUPIDITY”.
He sought to argue that the British decision, which has been supported by the US administration, as another reason why America had to take control of Greenland.
Trump has threatened tariffs against eight European nations including Britain, unless they agree to allow the US to buy Greenland.
But the UK government hit back, stressing that the Trump administration had “publicly welcomed” the deal over the Chagos Islands, with a statement by US Secretary of State Marco Rubio last May.
A UK government spokesperson said: "The UK will never compromise on our national security. We acted because the base on Diego Garcia was under threat after court decisions undermined our position and would have prevented it operating as intended in future.
"This deal secures the operations of the joint US-UK base on Diego Garcia for generations, with robust provisions for keeping its unique capabilities intact and our adversaries out.”
He added: "This Agreement has been publicly welcomed by the US, Australia and all other Five Eyes allies, as well as key international partners including India, Japan and South Korea."
Trump has previously voiced support for the agreement as it was being worked up, saying in February last year, when Sir Keir Starmer visited the White House: “I have a feeling it’s going to work out very well.
“They’re talking about a very long-term, powerful lease, a very strong lease, about 140 years.”
Cabinet minister Darren Jones, the Prime Minister’s Chief Secretary, also suggested that the US president may back down over the tariffs.
He said British businesses should not yet prepare for the 10% tariff due to come in on February 1 as it was still a “hypothetical”, with the levy due to rise to 25% in June.
Sir Keir had told the US president that a trade war was in no-one’s interests, Mr Jones added on ITV’s Good Morning Britain.
Just minutes later, news broke of the extraordinary message on Truth Social from Trump.
“Shockingly, our “brilliant” NATO Ally, the United Kingdom, is currently planning to give away the Island of Diego Garcia, the site of a vital U.S. Military Base, to Mauritius, and to do so FOR NO REASON WHATSOEVER,” he stated.
“There is no doubt that China and Russia have noticed this act of total weakness. These are International Powers who only recognize STRENGTH, which is why the United States of America, under my leadership, is now, after only one year, respected like never before.
“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.
“Thank you for your attention to this matter. PRESIDENT DONALD J. TRUMP”
Trump raised the temperature over Greenland even further by posting an image on Truth Social depicting him carrying a US flag on the Danish territory.
The US president, who is travelling to Davos, Switzerland, for the World Economic Forum, made the claims as he ramped up his rhetoric on acquiring the Arctic territory.
Diego Garcia, the largest of the Chagos Islands – a small archipelago in the Indian Ocean – is home to a strategically important military base jointly used by the US and the UK.
Britain has paid Mauritius to lease back Diego Garcia and the base for at least 99 years under the terms of the deal.
Responding to Trump’s message, Mr Jones stressed legislation was going through Parliament on the Chagos Islands deal and he doubted whether the UK would change its stance.
“What we have put in place is to secure that base 100 years by essentially leasing it and that protects our military capabilities in that important part of the world, both for us and for the Americans,” he told Times Radio.
“When we announced that we are able to secure this deal with the Mauritius government, the American administration and our other Nato allies welcomed it.”
Trump’s sudden public broadside to Sir Keir stands in contrast with the calm approach the PM and other European leaders have taken towards the US president in recent weeks over his ambitions to own Greenland.
It also cast into question the benefits of Sir Keir’s approach to dealing with the unpredictable president, of shying away from criticising him and flattering him.
Meanwhile, French President Emmanuel Macron told Trump that he could set up a G7 meeting in Paris on Thursday afternoon and that he did not understand what Trump was "doing on Greenland".
According screenshot messages that Trump post on Truth Social, Macron told the US president that he could invite the Ukrainians, the Danish, the Syrians and the Russians to participate on the margins of the meeting, and also invited Trump to have dinner with him in Paris on Thursday.
Trump's replies, if any, were not part of the screenshot that he posted.
France is pushing for Europe to prepare “bazooka” retaliatory measures if Trump imposes his threatened tariffs.
The White House and the Macron's office did not respond to a request for comment on the messages.
A source close to Macron said that the text message shared by Trump was authentic.
EU leaders are set to convene in Brussels on Thursday evening for an emergency summit following Trump's threats to impose new tariffs on several EU countries over his demand to acquire Greenland.
