U.S. doubles tariffs on steel and aluminum to 50%

The United States doubled its steel and aluminum tariffs to 50% Wednesday, casting a pall on a gathering of OECD ministers as President Trump's intensifying trade war weighs on the world economy. The boosted levies went into effect at midnight EDT.

Mr. Trump's sweeping tariffs on allies and adversaries alike -- including ones on imported steel and autos -- have strained U.S. ties with trading partners and sparked a flurry of negotiations to avoid the duties.

And the pressure is mounting as the Organization for Economic Cooperation and Development (OECD), a 38-nation grouping of mostly developed countries, cut its global growth forecast on the back of the Trump levies.