"We're talking about international security," he said. "Right now, you look at it, you have warships all over the place going through right along Greenland. We're not going to let that happen. We cannot let that happen. Or if it's going to happen, we have to be protective of our country. And more importantly, really, not only our country, of the world."
He added that the situation is more urgent because of the growth of modern-day weaponry, where 100 years ago, it would have been "less so" because of the "water roadways" around Greenland.
"They're opening up icebreakers out there," said Trump. "They're headed right into China, right into Russia, and we have no choice."