Donald Trump reveals cryptic plan to send 65,000-tonne Navy ship to Greenland - 'It's on the way!'

"It’s on the way," Mr Trump added, alongside an image of the USNS Mercy, a hulking hospital ship in the country's Navy.

He added that he was working with the "fantastic" Governor of Louisiana, Jeff Landry, on the idea.

Governor Landry also serves at the US special envoy to Greenland.

It remains unclear exactly what the President is planning.

However, earlier on Saturday, Danish military officials said a medical emergency aboard an American submarine in Arctic waters prompted an international rescue mission.

That appeared to have been the closest thing to a health emergency on the island.

The Danish Defence's Joint Arctic Command helped evacuate a US Navy crew member who needed immediate medical attention while the submarine was floating off the coast of Greenland.

According to reports, the sub was around seven nautical miles from the Greenlandic capital city of Nuuk.

The Joint Arctic Command shared details of the operation in an official statement - but did not reveal any details of the medical emergency or the sailor's condition.

Mr Trump's post suggests the emergency may be more widespread than reported.

GB News has approached the White House for more information regarding the post.

Mercy is a 65,000-tone, 1,000-bed hospital ship operated by the US Navy's Military Sealift Command.

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She began a one-year scheduled maintenance period at a shipyard in Mobile, Alabama, last July.

Before that, the vessel usually operated in the Pacific and Indian Oceans to provide emergency care for US forces and humanitarian disaster relief.

The President has cooled his interest in Greenland since tensions flared earlier this year.

A string of European leaders, including Denmark's Royal Family, have visited in the weeks since.

EU chief Ursula von der Leyen will head north in March - after Nato started a mission in the region in a bid to cool Mr Trump's ambitions.

At the Munich Security Conference in February, Sir Keir Starmer said the Royal Navy would patrol the waters off Greenland by the end of 2026.

The PM revealed Britain will send its carrier strike group to the north Atlantic and Arctic waters later this year - with HMS Prince of Wales, the Royal Navy's largest vessel, leading the deployment.

That news came just days before RAF chief Sir Harv Smyth warned the air force would struggle to operate in Arctic conditions.

Air Chief Marshal Sir Harv said decades of fighting in Afghanistan and Iraq meant the RAF was “incredibly good” in temperatures above 35C.

But he voiced his concerns that pilots and aircraft had lost their edge to fight effectively in the -30C conditions of the High North.