What a bizarre description of what the US did.

Greenland has been inching towards independence since the seventies, because that's the common ambition of greenlandic peoples and it's slow because there are rather deep ties between Denmark and Greenland. These ties are to some extent very negative for the greenlanders, they're generally discriminated against and have been viciously mistreated at times, but a quick clean cut would also be quite painful for them.

In the seventies Greenland joined the EU predecessor EEC with Denmark, quickly realised that europeans were emptying their fishing waters and in the early eighties left the union. It's the only entity to have done so. Then the independence process trudged on, they self-manage in many areas now, even more since a 2008 referendum where some 75% or so voted in favour of independence. Since 2009 there is a law that says that Greenland can become independent whenever they want, as long as it's approved by greenlander referendum and the danish parliament.

To the extent they're a colony international law also clearly gives them the right to unilaterally declare independence. A majority of greenlanders are likely still in favour, but a majority also would prefer to postpone it if it would result in worse living conditions, since that's what polls usually conclude.

Ignoring half a century of rather delicate politics and independence ambitions the US shat all over it and said that they wanted to buy it, and then several years later said that they might just annex instead. This is quite belligerent and nasty behaviour, which in my opinion should have caused european countries to start dumping US bonds and stop answering calls from the White House.