Donald Trump has been slammed for acting "extremely foolishly" and disrespected WW2 veterans over his desire to acquire Greenland.
Joining the People's Channel, the party's environment spokesman Tim Farron accused the US President of "lashing out over Greenland" by hitting out at the Chagos deal - which his administration previously approved last May.
In a scathing Truth Social post, Mr Trump declared the deal an "act of great stupidity" in Labour's bid to hand over sovereignty of the archipelago, which houses a UK-US military base, to Beijing ally Mauritius.
He added the deal was "another in a very long line of National Security reasons why Greenland has to be acquired" in the damning statement.
Yesterday, Sir Keir Starmer tried to soothe simmering US-European tensions, holding an emergency address claiming the ordeal regarding Greenland should be resolved "through calm discussion".
But, this morning, Mr Trump wrote: "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 continued: "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 surprising intervention completely contradicts the State Department's official position on the territory.
Mr Farron said Mr Trump's Chagos criticism was simply 'lashing out over Greenland'
|GETTY/GB NEWS
Last May, when Sir Keir Starmer confirmed the deal had been done, Secretary of State Marco Rubio said in a statement: "We commend both the United Kingdom and Mauritius for their leadership, vision, and commitment to ensure that Diego Garcia remains fully operational."
But the former leader of the Liberal Democrats hit out at the President's criticism on GB News, telling hosts Eamonn Holmes and Ellie Costello it was a "bizarre" situation.
"It was something that was fought for by our grandfathers and great-grandfathers in the bloody Second World War, and all the people at home who endured such utter torment for those six years, and to build a peace that was an enduring peace.
"And it's been thrown away by one man.
DONALD TRUMP LATEST:
- Nigel Farage slams Donald Trump's tariffs as 'wrong' and vows to 'have words' with ally - 'Not the way you treat your best friend!'
- Donald Trump brands Chagos deal 'act of GREAT STUPIDITY and total weakness' in major attack on Britain
- 'There's no going back!' Donald Trump warns Denmark 'can't protect Greenland' in ominous new threat
Mr Trump has slapped upcoming levies on seven European nations
|GETTY
Mr Farron said: "This is not about Chagos, this is just him lashing out over Greenland, which is a bizarre situation to find ourselves in.
"The Nato alliance has pretty much kept the peace, particularly in the Western world, for the last 80 years.
"Even if you are a person who would normally politically be favourable towards Donald Trump, surely this is the moment when you realise that the peace of the world is now being threatened by one man acting extremely foolishly?"
He added: "I mean, the reality is, yes, Greenland is significant militarily, strategically, and it belongs to a staunch Nato ally. America has troops on that island anyway."
Mr Farron added: "Anybody who's a true patriot this morning will be raising an eyebrow at Donald Trump and indeed, hopefully potentially standing up to him even more strongly than that.
"I've always thought, actually, in my experience, that the vice that traps most politicians is not the lurid stuff that ends up in the tabloids. It's vanity. I feel it's vanity."
After Europe doubled down on its military presence in the area to conduct training exercises, Mr Trump slapped 25 per cent tariffs on seven nations across the continent, including the UK, France, Norway and the Netherlands.
The levies will come into effect on February 1.