The intensifying trade fight between the U.S. and China didn’t come out of the blue. American frustration has long been building over China’s failure to live up to its commitments when it joined the World Trade Organization in 2001.

But President Trump’s unilateral tariffs risk a Pyrrhic victory that damages global trading rules that have broadly served U.S. interests. There may be a more effective solution: threaten China with expulsion from the WTO.

Calling...