Amid the quiet but accelerating contest for Arctic influence, the United States and Denmark have reached a security agreement concerning Greenland — a vast, resource-rich island that sits at the crossroads of global ambition and shifting ice. President Trump announced the deal on Friday, though its precise terms remain undisclosed, with both Copenhagen and Nuuk indicating a formal signing is forthcoming. The agreement reflects a deeper truth of our era: that the warming of the planet is not only an environmental reckoning but a geopolitical one, reshaping which nations hold sway over the passa