Early Friday morning, shortly before tweeting casting tips to Saturday Night Live, Donald Trump sent this statement out into the universe:

It’s disturbing on a number of levels, not the least of which is his use of a phrase parents generally reserve for their naughty children (“Don’t get cute with me, missy!”) applied here, by the president of the United States, to another country. But it’s the notion that “trade wars are good, and easy to win” that is truly terrifying, considering the consensus is that trade wars are, in fact, neither good nor easy to win—in fact, more often, everyone loses. Over the past 13 months, Trump’s non-crazy advisers have reportedly attempted to hammer this idea into his head. Those tutorials were officially declared a failure on Thursday, however, when the president surprised nearly all of the people who work for him by declaring his intent to impose tariffs of 25 percent on steel and 10 percent on aluminum. Now, in the wake of Trump’s impromptu announcement—one that was supported internally by only Commerce Secretary Wilbur Ross, and adviser Peter “Free trade causes infertility” Navarro— world leaders have taken the opportunity to let the president know exactly what they think of his plan and—spoiler alert—they do not think trade wars are “good.”

Li Xinchuang, vice secretary general of the China Iron and Steel Association, called the move “extremely stupid” and “a desperate attempt by Trump to pander to his voters, which . . . in fact runs counter to his ‘America First’ pledge.” Bernd Lange, head of the European Parliament’s trade committee, commented, “with this, the declaration of war has arrived,” shading the “mercantile model in [Trump’s] head that dates back 200 years.” Ildefonso Guajardo, Mexico’s economy minister, has reportedly “made it clear that if included [in the tariffs], Mexico will have no other option than to react.” Even Canadian Prime Minister Justin Trudeau said any U.S. tariffs on steel and aluminum imports would be “absolutely unacceptable,” noting that his government has been trying to “impress upon the American administration [that] . . . these proposals are going to hurt them every bit as much as they are going to hurt us.” But it was European Commission President Jean-Claude Juncker who knew how to really hit us where it hurts. “We will put tariffs on Harley-Davidson, on bourbon and on blue jeans—Levi’s,” Juncker said Friday. “We cannot simply put our head in the sand.”

Those threats of retaliation became a bit less theoretical when Wilbur Ross appeared on CNBC Friday and, bearing various canned goods for some light prop comedy, said of the options he presented, “the president chose one—which was [to] put broad tariffs on all products from all countries.” If that is indeed the case, it would mean that allies who’ve been fighting to be exempt, such as Japan and South Korea, could be much more likely to fight back. But according to Ross, who seemingly stepped into a 7/11 for the first time in his life today, that’s not a problem. “In any war there may be a few casualties,” he said. “That just comes with the nature of the beast.”