He made the comments during a meeting with oil executives at the White House Friday.
Trump said that he would like to make a deal “the easy way” to acquire Greenland, because if the US doesn’t own it, he claimed Russia or China will take over it.
“If we don't do it the easy way, we're going to do it the hard way,” he said, without explaining what the “hard way” entailed.
Trump also added that he is “a fan” of Denmark but questioned the country's claim to Greenland.
"I'm big fan, but you know the fact that they had a boat land there 500 years ago doesn't mean that they own the land," Trump said. "I'm sure we had lots of boats go there also."
Trump and his officials have long indicated they want to control Greenland to enhance American security and explore business and mining deals.
After the White House indicated military options are being considered, Denmark's prime minister warned that would spell the end of Nato.
To that, Trump said: "I'm all for Nato. I saved Nato. If it weren't for me, you wouldn't have Nato right now.
"But we're not going to allow Russia or China to occupy Greenland. And that's what's going to happen if we don't.
"So we're going be doing something with Greenland either the nice way or the more difficult way."
