"The US Geological Survey estimates that onshore northeast Greenland (including ice-covered areas) contains around 31 billion barrels of oil-equivalent in hydrocarbons – similar to the US’s entire volume of proven crude oil reserves."
Source: https://theconversation.com/greenland-is-rich-in-natural-res...
Denmark does not (since 2009) control Greenland's minerals, nor take revenues from resource extraction[0,1]; and Greenland's democratic government has in fact totally banned oil exploration[2].
[0] https://www.politico.eu/article/europe-neglect-greenland-min... ("In 2009, Denmark handed Greenland's inhabitants control of their natural resources...")
[1] https://english.stm.dk/the-prime-ministers-office/the-unity-... ("Revenues from mineral resource activities in Greenland are to accrue to the Self-Government. Such revenues will have influence on the size of the Danish Government subsidy, cf. section below on the economic arrangement.")
[2] https://news.ycombinator.com/item?id=27871672 ("Greenland bans all oil exploration (cbc.ca)" (2021))
> "Global warming means that retreating ice could uncover potential oil and mineral resources which, if successfully tapped, could dramatically change the fortunes of the semi-autonomous territory of 57,000 people."
> ""The future does not lie in oil. The future belongs to renewable energy, and in that respect we have much more to gain," the Greenland government said in a statement. The government said it "wants to take co-responsibility for combating the global climate crisis."
Regardless, the US isn’t taking over Greenland for its oil. That is just ridiculous and there would be far easier targets to go after if that was the case.