If President Donald Trump is serious about bolstering the U.S. presence in Greenland, he has options ¡ª but he may still want the most provocative one.

Trump has insisted the United States needs the strategically located island, with Russia and China increasing military activities nearby and Arctic ice melting due to climate change.

He has repeatedly refused to rule out force to seize Greenland, infuriating Denmark, a steadfast U.S. ally and founding NATO member that controls the autonomous island.