China was not Mr. Pompeo’s only target on Monday, and his decision to issue his global warning before the Detroit Economic Club suggested that a sweeping investigation into car imports could result in even more tariffs. The Trump administration has already imposed tariffs on steel and aluminum from its closest trading partners, and Mr. Pompeo said that “asymmetric trade relationships” with Canada, Europe, Japan and Mexico needed to change.

“It’s a simple moral principle, this idea of fairness,” Mr. Pompeo said.