Let me begin by quoting, in full, a letter that the president of the United States of America sent yesterday to the prime minister of Norway, Jonas Gahr Støre. The text was forwarded by the White House National Security Council to ambassadors in Washington, and was clearly intended to be widely shared. Here it is:

One could observe many things about this document. One is the childish grammar, including the strange capitalizations (“Complete and Total Control”). Another is the loose grasp of history. Donald Trump did not end eight wars. Greenland has been Danish territory for centuries. Its residents are Danish citizens who vote in Danish elections. There are many “written documents” establishing Danish sovereignty in Greenland, including some signed by the United States. In his second term, Trump has done nothing for NATO—an organization that the U.S. created and theoretically leads, and that has only ever been used in defense of American interests. If the European members of NATO have begun spending more on their own defense (budgets to which the U.S. never contributed), that’s because of the threat they feel from Russia.

Yet what matters isn’t the specific phrases, but the overall message: Donald Trump now genuinely lives in a different reality, one in which neither grammar nor history nor the normal rules of human interaction now affect him. Also, he really is maniacally, unhealthily obsessive about the Nobel Prize. The Norwegian Nobel Committee, not the Norwegian government and certainly not the Danish government, determines the winner of that prize. Yet Trump now not only blames Norway for failing to give it to him, but is using it as a justification for an invasion of Greenland.

Think about where this is leading. One possibility, anticipated this morning by financial markets, is a damaging trade war. Another is an American military occupation of Greenland. Try to imagine it: The U.S. Marines arrive in Nuuk, the island’s capital. Perhaps they kill some Danes; perhaps some American soldiers die too. And then what? If the invaders were Russians, they would arrest all of the politicians, put gangsters in charge, shoot people on the street for speaking Danish, change school curricula, and carry out a fake referendum to rubber-stamp the conquest. Is that the American plan too? If not, then what is it? This would not be the occupation of Iraq, which was difficult enough. U.S. troops would need to force Greenlanders, citizens of a treaty ally, to become American against their will.

For the past year, American allies around the world have tried very hard to find a theory that explains Trump’s behavior. Isolationism, neo-imperialism, and patrimonialism are all words that have been thrown around. But in the end, the president himself defeats all attempts to describe a “Trump doctrine.” He is locked into a world of his own, determined to “win” every encounter, whether in an imaginary competition for the Nobel Peace Prize or a protest from the mother of small children objecting to his masked, armed paramilitary in Minneapolis. These contests matter more to him than any long-term strategy. And of course, the need to appear victorious matters much more than Americans’ prosperity and well-being.

The people around Trump could find ways to stop him, as some did in his first term, but they seem too corrupt or too power-hungry to try. That leaves Republicans in Congress as the last barrier. They owe it to the American people, and to the world, to stop Trump from acting out his fantasy in Greenland and doing permanent damage to American interests. He is at risk of alienating friends in not only Europe but also India, whose leader he also snubbed for failing to nominate him for a Nobel Prize, as well as South Korea, Japan, Australia. Years of careful diplomacy, billions of dollars in trade, are now at risk because senators and representatives who know better have refused to use the powers they have to block him. Now is the time.