Explained | All you need to know about American base on Greenland

Nuuk, Greenland: Once called Thule Air Base, now known as Pituffik Space Base, this US-operated installation in northwestern Greenland is one of the most strategically important military sites in the world -- even if most Americans have never heard of it.

"It is quite literally the outermost eye of American defense," said Peter Ernstved Rasmussen, a Danish defense analyst. "Pituffik is where the US can detect a launch, calculate the trajectory and activate its missile defense systems. It's irreplaceable."

The outpost is getting new attention as President Donald Trump, who has vowed to make Greenland part of the United States, sends a high-level delegation to the island this week. The visitors will include Vice President JD Vance, who said Tuesday that he intended to visit "our guardians" in the Space Force while there.

About 150 US Air Force and Space Force personnel are permanently stationed at Pituffik (pronounced Bee-doo-FEEK). They handle missile defense and space surveillance, and the Upgraded Early Warning Radar based here can detect ballistic missiles in their earliest moments of flight.

Each summer, about 70 members of the New York Air National Guard fly into Pituffik to support science missions. Using the US military's only ski-equipped aircraft, the LC-130, they deliver researchers and supplies to camps on the ice sheet.

Pituffik is the only US military base on Greenland.

The History

The US military presence in Greenland began during World War II, when Greenland was a Danish colony. After Nazi Germany occupied Denmark in 1940, Greenland was suddenly isolated and undefended. The United States struck a quiet deal with Denmark's ambassador in Washington -- bypassing the German-controlled government in Copenhagen -- for US troops to build airfields and weather stations on the island.

By 1941, US forces had landed, setting up defenses and scanning the North Atlantic for German submarines. A decade later, Denmark and the United States formalized the arrangement with a defense treaty granting Washington broad rights to operate military facilities on the island. Greenland is now a semiautonomous part of Denmark, which, like the United States, is a NATO country.

During the Cold War, Thule became a key Arctic outpost. From here, long-range US bombers could reach the Soviet Union, and massive radar systems were built to detect missiles crossing the polar route -- the shortest path between the two superpowers.

One of the era's strangest experiments was Camp Century, a nuclear-powered base built under the ice in the late 1950s as part of a secret project called Iceworm. The plan was to test whether nuclear missiles could be hidden and launched from beneath the surface.

"It was Cold War ambition at its wildest," Rasmussen said. "They built a nuclear-powered base in one of the most hostile environments on Earth just to see if it could be done."

The ice proved too unstable, and the base was abandoned. But the waste -- including radioactive material and diesel -- is still buried, and scientists warn that warming temperatures could eventually expose it.

The base also left a lasting mark on Greenland's Indigenous population. In 1953, about 130 Inuit were forcibly relocated from their homes near Thule to a harsher settlement farther north, poorly suited for traditional hunting. Compensation came decades later, but resentment remains.

The base's name changed two year ago from Thule to Pituffik, which means in Greenlandic "the place we tie our dogs."

The Location

Pituffik sits above the 76th parallel on Greenland's northwest coast, about 750 miles from the North Pole. It's one of the most remote military installations on Earth.

The nearest settlement, Qaanaaq, is more than 70 miles away and home to fewer than 650 people. Many hunt seals, walrus and, occasionally, polar bears to survive.

In winter, the sun disappears for weeks, and temperatures drop below minus 30 Fahrenheit (minus 34 Celsius). Despite the conditions, Pituffik's airfield runs year-round. Ships can reach the base only during a narrow summer window when the sea ice temporarily retreats.

The Base's Technology

Pituffik is part of a global web of US defense infrastructure and a crucial station. Military experts say that as new threats like hypersonic missiles emerge, the early-warning systems at Pituffik are indispensable.

"Hypersonic missiles don't go into space; they fly low, they maneuver, and we have no way to intercept them once they're launched," explained Troy J. Bouffard, a retired US Army officer and Arctic defense expert. "That makes early warning more important than ever -- and that's where Pituffik comes in."

If a missile were launched from Russia or China toward North America, it would, Bouffard said, most likely pass over the Arctic.

Pituffik's ground-based sensors are crucial in that case, said Bouffard, because satellites don't work well in high latitudes.

Lasers don't work in the Arctic, either, he added. "The air columns are full of ice crystals -- basically, tiny mirrors -- and lasers and mirrors don't get along," he said.

Bouffard sees Pituffik's role expanding beyond radar.

"It could also serve as a forward staging base or a key line of communication," he said. "The more forward these locations are, the more useful they are."