On Sunday, Iranian President Hassan Rouhani said in a televised speech to a domestic audience that the United States cannot prevent his country from exporting oil, adding that “peace with Iran would be the mother of all peace and war with Iran would be the mother of all wars.”

Donald Trump could have responded like an unflappable world leader. Instead, he replied in the favorite style of easily baited idiots: He posted an all-caps tweet. “To Iranian President Rouhani,” he wrote. “NEVER, EVER THREATEN THE UNITED STATES AGAIN OR YOU WILL SUFFER CONSEQUENCES THE LIKES OF WHICH FEW THROUGHOUT HISTORY HAVE EVER SUFFERED BEFORE. WE ARE NO LONGER A COUNTRY THAT WILL STAND FOR YOUR DEMENTED WORDS OF VIOLENCE & DEATH. BE CAUTIOUS!”

By responding that way, Trump dramatically inflated the reach of Iranian words that would’ve otherwise been ignored. And he spoke as though rhetoric that wasn’t even particularly bellicose is itself good reason for war.

The episode reflects poorly on his fitness to be president. Maybe he is bluffing—that is to say, maybe he wouldn’t, in fact, launch a possibly catastrophic war over mere words, preferring to ground such a momentous decision in the actual substance of American national security. If so, he spoke recklessly: America gains exactly nothing from a bluff of that sort, and risks exposure if Iran chooses to call him on his words. Trump foolishly put the U.S. in a reactive position.