U.S. President Donald Trump said "massive" oil, gas and mineral exploration is set to begin in "our new and beautiful Greenland " early Wednesday, though it wasn't clear what developments he was referring to on an island where resource extraction has stymied companies for decades.

Despite Trump's optimism, the harsh climate of Greenland - a self-governing territory of Denmark, rather than a part of the United States - as well as a lack of infrastructure have foiled all previous attempts to extract so-called rare earth minerals, as well as oil and gas.

No efforts have ever progressed beyond the exploratory stage.