Donald Trump's trade advisers were finalizing plans on Wednesday for the reciprocal tariffs the U.S. president has vowed to impose on every country that charges duties on U.S. imports, ratcheting up fears of a widening global trade war.

Chinese tariffs on U.S. products including LNG, coal and agricultural equipment were imposed Monday, in response to Trump’s 10 percent blanket levy.

The European Union plans to retaliate against the United States for new steel and aluminum tariffs, adding another element to rising global trade tensions. "Unjustified tariffs on the EU will not go unanswered—they will trigger firm and proportionate countermeasures,