This too is, perhaps deliberately, vague. One option the EU has is to pursue joining countries like Canada and Mexico, which have been exempted from the tariffs. “I have the right to go up or down depending on the country, and I’ll have a right to drop out countries or add countries,” Trump said, noting that his generosity, even to traditional allies, could be limited. “If you look at NATO, where Germany pays 1 percent and we are paying 4.2 percent of a much bigger GDP, that’s not fair. NATO countries, some owe billions and billions of dollars. Defense is also part of trade—to a certain extent they go hand-in-hand.”

But if somehow the bloc doesn’t manage to meet the standards “friendly nations” must to get out of the tariffs, it has the potential to get much less friendly. After President George W. Bush attempted to impose a 30-percent steel tariff in 2002, the World Trade Organization ruled that the move violated global trade rules, enabling the EU to threaten retaliation with its own tariffs. Those ones were set to target Harley Davidson motorcycles, Michigan-manufactured cars, and oranges from Florida, where the then-president’s brother, Jeb Bush, was governor. The targeted goods were also produced in electoral swing states. Bush ultimately backed down.

This time, the bloc outlined more than 100 possible products this week—$3.5 billion worth of them—that it might target for tariffs, including some familiar ones: bourbon whiskey, Harley Davidson motorcycles, oranges. And again, the choices are not random, especially given upcoming midterm elections in the U.S. “Harley Davidson motorcycles and bourbon, which come from Wisconsin and Kentucky, are not coincidentally the home states of the Republican leaders in the House and the Senate,” Matthew Oxenford, a researcher on transatlantic economic relations at the London-based Chatham House, told me. “That’s very consciously being done with an eye towards influencing a particular political player. Florida oranges is another thing because Florida is always a close state in U.S. elections.”

André Sapir, a senior fellow at the European economic think tank Bruegel, said that before the EU could follow through on such a threat, if it wanted to, the bloc would first go to the WTO, where it would charge the U.S. with running afoul of global trade rules. Sapir, a former economic adviser to the president of the European Commission, told me it was the WTO’s ruling against U.S. steel tariffs in 2003 that “gave the green light to the EU and other parties to take countermeasures.” This time around, the EU is expected to call into question the Trump administration’s assertion that the tariffs were imposed to protect the country’s national security—a “safeguard” action that, though considered valid under certain conditions, is rarely invoked. “We cannot see how the European Union, friends and allies in NATO, can be a threat to international security in the U.S.,” Cecilia Malmström, the EU trade commissioner, said Wednesday, adding: “From what we understand, the motivation of the U.S. is an economic safeguard measure in disguise, not a national security measure.”