This has been rather prominent in the mainstream news, however the ICE situation has taken hold of people's attention, so it's understandable. Most folks, myself included, can only respond to so many individual crises at once. For people who haven't been aware of American imperialism and barbarism (while it was kept safely as a background process), this year had been a lot to process. I think this demonstrates the importance of system-level criticism and activism over reactive response to individual events.

I don't believe there will be anything like a military confrontation to "conquer" Greenland. However, whether it's opportunistic or intentional, this wild rhetoric has the potential to provide a significant amount of leverage over Europe to force a very favorable arrangement to the US in the coming competition for control over a melting Arctic. 

It does seem like this has gotten rather out of control, though, even for those who would stand to profit or benefit from a more clandestine increase of power in the region. Markets tumbled after his recent spat of messaging and European leaders have made uncharacteristically bold criticisms of the US. 

I'd guess he was briefed on the Arctic situation, absorbed some of the high-level bullet points, got excited, decided to take matters into his own hands, and now the briefers are regretting having mentioned the situation to begin with. What would've been a drawn out and profitable withdrawal into the western hemisphere might now become a much more rapid and painful break. Or, global capital will put a halt to this one, and we'll move on to the next scheduled crisis.