Greenland's only US military base was once a tightly guarded secret at the height of the Cold War.
The Pituffik Space Base was built to counter the then-Soviet Union's missiles and bombers over the Arctic in the 1950s.
Now it sits at the heart of a disagreement that could tear a fragile NATO alliance apart.
US President Donald Trump has been threatening to take over Greenland, which is part of the Kingdom of Denmark, possibly by military force.
Greenland and Denmark say it is not for sale and that threats of force are reckless.
In a show of support, several European allies have started sending troops to the Arctic island to create a "larger and more permanent" NATO presence.
But the White House has said the presence of European troops will not impact Mr Trump's "goal of the acquisition of Greenland at all".
Here is what we know about the US military footprint in Greenland, and how the increase of troops from Denmark and its allies stacks up.
History of the US military presence in Greenland
The United States military presence in Greenland dates back to World War II.
In 1941, the Danish ambassador signed a treaty allowing the US military access to Greenland to protect the Arctic island from Nazi Germany.
"Agreement between the United States of America and Denmark respecting the defense of Greenland. Signed April 9, 1941," the treaty reads.
"…Defense of Greenland against attack by a non-American power is essential to the preservation of the peace and security of the American Continent and is a subject of vital concern to the United States of America and also to the Kingdom of Denmark."
The treaty — still active today — saw the emergence of US bases in western and southern Greenland that were vital refuelling posts for planes flying across the Atlantic.
US soldiers numbering in their hundreds were stationed in southern Greenland to protect the world's largest cryolite mine, which was critical to airplane infrastructure during the war.
The US had dozens of military bases across the island, including Camp Century, Blue West and Blue East.
In 1951, the US unveiled the top-secret Thule Air Base, designed to defend against the Soviet Union during the Cold War.
It became its most prominent base in the territory, housing bombers, fighters, nuclear missiles and tens of thousands of soldiers.
It is on the north-western coast of Greenland, about 1,200 kilometres north of the Arctic Circle and 1,524km south of the North Pole.
It also sits about 1,500km north of Greenland's capital, Nuuk.
In 2023, the base was renamed to Pituffik Space Base to acknowledge Greenlandic cultural heritage and reflect its role in the newly formed US Space Force.
What is the US presence now?
The Pituffik Space Base is the only US base that remains in Greenland today, used to support missile warning and defence and space surveillance missions.
It is the US military's northernmost installation, and is operated by the 821st Space Base, and a part of Space Base Delta 1.
There are about 200 US troops stationed at the base, according to Danish officials.
Last June, the Trump administration shifted the responsibility of Greenland from the US European Command to the US Northern Command.
The Pentagon said at the time it was done to strengthen the ability to defend the US homeland and contribute to the defence of the western hemisphere.
Professor Andreas Østhagen from Norway's Fridtjof Nansen Institute said the Trump administration's rhetoric surrounding Greenland did not match its presence on the Arctic island.
"If you take that argument seriously about a wider security threat or a wider concern when it comes to Russia or China, then you would imagine that the US would just utilise the opportunity it already has to station more troops," Professor Østhagen told the ABC.
"Whether it's in the Pituffik Space Base or in other parts of Greenland."
Mr Trump has cited national security concerns as his reason for the US needing to acquire Greenland.
In recent days, he has been repeating his justifications for a takeover, claiming Russian and Chinese ships were posing threats.
"If you take a look outside of Greenland right now, there are Russian destroyers, there are Chinese destroyers and, bigger, there are Russian submarines all over the place," he said.
"We're not gonna have Russia or China occupy Greenland, and that's what they're going to do if we don't."
But Professor Østhagen, whose research focuses on political dynamics in the Arctic, dismissed the presence of Russian and Chinese ships near the island, saying the threat to Greenland was "insignificant".
"You could, of course, say that there could be a Russian threat due to ballistic missiles or submarines," he said.
"But Greenland is not more under threat from Russia than other parts of the Arctic.
"Whether it's the Canadian Arctic, or Iceland, or even Alaska. So Greenland is nothing particular when it comes to Russian threats."
He added that China's presence was too far away from Greenland, and there had not been much activity from Beijing in that part of the Arctic.
"The Chinese threat is primarily in the North Pacific and the Bering Sea stretching towards the Arctic Ocean," he said.
"Then, the other part of the Arctic where you see Russia operating is the European part of the Arctic. So, off the coast of the European continent where you have Norway, Sweden, and Finland having to deal with increased Russian military activity.
"So, it's not really Greenland that is in the middle of all this."
How Denmark and allies are responding to Trump
Several NATO allies, including Germany, France, Norway, Finland and Sweden, have sent armed forces to Greenland at Denmark's request.
France has already sent about 15 soldiers from its mountain infantry for a military exercise in Greenland's capital Nuuk, with more to follow.
Germany deployed a reconnaissance team of 13 personnel.
Denmark's defence minister Troels Lund Poulsen said the increased military presence in the Arctic alongside allies was a necessity due to the current security environment.
Prior to the announcement, Denmark had about 150 military and civilian personnel working at its Joint Arctic Command on the island.
Mr Poulsen added that he did not have a final figure for the envisaged expansion of NATO's presence in Greenland.
"But it is clear that we now will be able to plan for a larger and more permanent presence throughout 2026," he said.
"That is crucial to show that security in the Arctic is not only for the Kingdom of Denmark, it is for all of NATO."
Professor Østhagen saw the move by Denmark and its allies as a symbolic gesture to show there was unity within Europe.
"They're meant to signal to the US that there's a certain threshold or a certain cost to these actions by the United States," he said.
But the White House has said sending European troops to Greenland will not change the Trump administration's intentions surrounding the territory.
"I don't think troops in Europe impact the president's decision-making process, nor does it impact his goal of the acquisition of Greenland at all," White House spokesperson Karoline Leavitt said.
Professor Østhagen said the continued pursuit of Greenland could lead to the breakdown of diplomatic and security relations between the US and other NATO allies.
"If the US were actually to push this further, not only rhetorically, but also by other means, use of military force, then the downfall would be the break-up of the NATO alliance," he said.
"You can't trust the US as a security guarantor anymore."
