Trump is very keen on Greenland.
Europe is very keen on stopping Russia in Ukraine and from making moves on its European neighbours.
Just randomly thinking that Trump sees this as an opportunity for negotiating a deal; He gains either control of or an agreement on greater US involvement in Greenland (military and mineral rights) and in return helps bring about a peace deal in Russia with long term support for Ukraine and, of course, mineral rights and rebuilding contracts.
The BBC news tonight says there is optimism among European leaders on US support for a peace deal, and Trump has made further statements about his designs on Greenland......Mmmm