You did not need any more strengthening of any military treaties with Denmark, the US could already open as any military bases on Greenland, there was nothing stopping you from doing that, sending more of your army there to deter China or Russia, or whatever else. Here, https://people.com/donald-trump-wants-ownership-greenland-ps... He is saying he needs to own it to personally feel good. How does this make sense diplomatically?
Any excuses you make will not make him look better or make him look like he can be trusted. If you want to achieve something in international politics have to be made carefully, not by threatening to annex Canada or parts of your allied countries.
Your president is just destroying the good image and goodwill towards the US with his 'negotiation style'. His style is childish bullying and temper tantrums, he can not be taken seriously as a reliable partner when he can say one thing today, and tomorrow say something totally different, even if you think you have reached an agreement with him on something.