The Trump tariffs are now clawing back tax savings at a rate of roughly $10.6 billion per year. The levies already in place include 25% on steel (imports in 2017 were an estimated $23.4 billion), 30% on solar panels ($8.5 billion), 10% on aluminum ($18 billion) and 20% on washing machines ($1.8 billion).

That’s chump change compared with what may be coming. On July 6, a 25% tariff kicks in on 818 Chinese imports worth $34 billion, costing Americans another $8.5 billion a year. If China retaliates, Mr. Trump has said he’ll slap a 10% tariff on an additional $200 billion of Chinese exports. The president warned last week that if Beijing responds a second time, he could levy a tariff on $200 billion more in Chinese exports. And an administration proposal for a 25% tariff on 284 Chinese exports to the U.S., whose value was $16 billion in 2017, is pending.

When the European Union imposed tariffs on selected American goods after being hit with U.S. steel and aluminum tariffs, Mr. Trump threatened a 20% tariff on cars imported from the EU. The administration hasn’t been clear whether this would hit only auto sales—whose value in 2017 was $43.4 billion—or also include parts, valued at $14.5 billion.