President Trump has threatened to increase Mexico’s tariff rate to 30 percent starting Aug. 1, claiming the country hasn’t sufficiently tackled drug cartels.

The 30% tariff on European goods threatened by U.S. President Donald Trump would, if implemented, be a game-changer for Europe, wiping out whole chunks of transatlantic commerce and forcing a rethink...

The downside risks of that bet have become clearer in recent days.