London —  President Trump has called the U.K.'s decision to hand over the Chagos Islands to Mauritius - a deal his administration previously supported - an act of "great stupidity" that further justified his desire for the U.S. to acquire Greenland . One of the islands, Diego Garcia, is the site of a key U.K.-U.S. military base in the Indian Ocean. "Shockingly, our 'brilliant' NATO Ally, the United Kingdom, is currently planning to give away the Island of Diego Garcia, the site of a vital U.S.