President Trump said Thursday he will impose a 5% tariff on Mexican goods—and will keep increasing trade sanctions each month until Mexico cracks down on Central American migrants heading for the U.S. border. The announcement caused the Mexican peso to plunge against the dollar, rattled markets around the world and set off fears of a broader trade war. Trump’s tariff threat could derail a trade deal known as the United States-Mexico-Canada Agreement, negotiated as a successor to NAFTA at Trump’s insistence. Trump announced his plans for tariffs just hours after Mexican President Andrés Manuel López Obrador sent lawmakers the renegotiated deal for ratification. In a statement, AMLO condemned Trump’s immigration actions and called his slogan “America First” a fallacy.