There is nothing the Europeans and Denmark can do if Trump wants to take Greenland. Denmark and the EU will just have to bend over and take it up the ass by daddy Trump without lube. The U.S has always wanted Greenland, and have in the past attempted to buy the island twice in 1867 and after WWII. Both times failed, but with how the geopolitical climate is evolving at an accelerated rate, the U.S may force Denmark and the Europeans to capitulate to a sale price, or the U.S will take it by force. The U.S is trying to build a sustainable independent supply chain, and resources such as Venezuela oil, iron ore, natural gas, and rare earths in Greenland, and the future Artic passage in the Northern sea route as the climate warms will also expose even more oil and gas reserves of which the U. S will need to help supply cheap energy and materials for reindustrialization. Not to mention, new exposed landmass in the Artic will also be an area of contention, which, with the acquisition of Greenland, will give the U.S a legitimate contention to expand physically, militarily, and economically into the Artic as it thaws. This will help the U.S secure resources it needs to fuel both its economy and military and to also keep those resources away from rival powers like China and Russia, and even the EU-- the Artic is part of the new Great Game of the 21st century, similar to what the Great Game of the 19th and 20th century was in Central Asia.