The free-trade era is over. U.S. President Donald Trump's tariff letters show that tariffs - to protect domestic industries and to raise revenue for a deeply indebted government - are the way forward.

President Donald Trump on Saturday threatened 30 percent tariffs on two major U.S. trading partners — the European Union and Mexico.

President Trump is pushing through with his tariff agenda, unveiling a new batch of letters to country leaders outlining ...