People keep mentioning the Ukraine support situation as being a catalyst here, but that is abolutely not the case. Ukraine is not a longstanding ally and member of NATO.
What has damaged trust in the US as a provider of military equipment is threats to annex Canada and Greenland, statements that Europe has to look after its own defence, public and private statements of current administration showing utter loathing and contempt directed at Europe, and tariff wars.
If you repeatedly punch your friends in the stomach, don't be surprised if they start avoiding you.
A few comments if I may. A standard business negotiating tactic in the U.S. is making outrageous demands. Business information is closely held. It is private. What happens in my own industry, for example, is very strict behavior online against making any comment about competitors. Such comments can and will be used against you and usually by anonymous people looking to harm your interests. And if people reject those outrageous demands, you walk away. Sometimes, though, they might accept.
The situation with Canada and Greenland goes back to the end of the Second World War. The Soviet Union became the new enemy in 1945. Britain was so alarmed that Prime Minister Churchill asked for and got a plan to attack the Soviet Union in 1945. It was called Operation Unthinkable.
In 1949, the Soviets detonated their first atomic bomb. The U.S. knew they had B-29s which they copied as the Tu-4. This bomber was now a significant threat. The Soviet plan was to fly them over the North Pole and across Canada. So the U.S. military began constructing lines of radars across Canada. First, Pinetree, followed by the Mid-Canada Line, followed by the northernmost Distant Early Warning Line which included Greenland. By the time NORAD was established, Canada understood its position in North American Air Defense.
"I think it is wrong to leave the impression with the Minister and the government that our air defence plan is primarily for the defence of Canadian territory when in fact, any defence of Canadian territory is but a by-product or extra dividend to the main purpose, which is the defence of SAC bases and northeastern United States."
-- Chief of the General Staff Lieutenant-General H.D. Graham, in a top-secret letter to Chairman Chiefs of Staff Charles Foulkes, August 21, 1958.
From page 71 of Requiem for a Giant by Palmiro Campagna.