We obviously don't think it's vital to our national security or else we wouldn't have closed all the bases we used to have there.
(Meanwhile, if you checked Marco Rubio's browser search history, I guarantee you'd find "map projection that makes cuba look huge".)
I would also point out that ratified treaties, such as the North Atlantic Treaty, have the force of law in the US.
So any order of hostilities against Danish territory is prima facie, de facto and de jure, cut and dried, no two ways around it and any way you slice it, definitionally an illegal order.
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