It seems you can also just lie to help him save face, like Canada did when it agreed it would adopt very strict border control policies to stop "drugs coming into the USA," and listed out steps that all were just existent Canadian laws and policies.
The problem that US generals have right now is that Trump has gotten the idea that the US (viz., he himself, in his mind) ought to literally own Greenland and he does know how real estate works. Treaties, mineral deals, guarantees for additional military bases that would mean de facto control over Greenland would work with a rational person. However, they won't work with someone who insists on buying or annexing a country to own its territory.
Yeah, another strategy is to just give him something he can claim as a W even if it's bullshit, or to glaze him enough. He's so hyperfixated on owning Greenland though, that I'm not sure those will work this time.
