President Donald Trump has his eyes on Greenland — and he may not be the only one — but it begs the question: Why does he want to purchase the massive frozen island off the coast of mainland Europe?

Danish Prime Minister Mette Frederiksen shot down Trump’s ideas of buying Greenland, calling them “absurd,” according to CNBC. The back-and-forth has seemingly created another rift between the United States and a longstanding international ally in Denmark. The two leaders were scheduled to meet, but Trump postponed the meeting after Frederiksen’s comments about buying the island.

But there’s no ignoring the geopolitical importance of the largest island in the world. Melting polar ice caps have created new North Atlantic shipping lanes around Greenland that can greatly reduce maritime travel times.

Not to mention the vast amount of natural resources that are nestled safely on the island that 80% of is covered in ice. Resources include coal, zinc, copper, iron ore and other rare minerals that are vital in the development of technology and other products.

Trump is not the only interested party, either. China, the president’s ultimate trade foe at the moment, has expressed the desire to create what it calls a “Polar Silk Road” along those new shipping lanes. In 2018, China considered building airports and mining facilities on the island but it withdrew the offer, according to CNBC.

“If (had) a significant investment in a country that is so strategically important for so many countries, they would have influence there,” Michael Sfraga, director of the Polar Institute at the Wilson Center, told CNBC in an interview.

“If you invest a lot in a small island country, you could have a lot of sway there.”

Denmark showed some opposition to China’s interest in Greenland in a report to the Pentagon earlier this year, citing concerns of an increased Chinese military presence.

“Civilian research could support a strengthened Chinese military presence in the Arctic Ocean, which could include deploying submarines to the region as a deterrent against nuclear attacks,” the report said.

The U.S. has had a deal since World War II with Greenland that allows troops to be housed on the island, and Thule Air Base is America’s northernmost post in the world. A deal with another country could threaten those strategic positions.