U.S. stocks followed indexes down around the globe Wednesday on fears of a trade war, as China swiped back at U.S. tariffs announced a day earlier. The Dow Jones industrial average plunged 510 points after opening before starting to climb back, The Wall Street Journal says. China said it would slap 25% duties on 106 American product categories, including key items such as soybeans, airplanes and cars. The move followed a U.S. threat for tariffs of the same magnitude on 1,300 product types — “the most aggressive challenge in decades to Beijing’s trade practices,” per The Wall Street Journal. Both plans target $50 billion worth of goods and come after a tit-for-tat over metal imports last month. China didn’t say when the new tariffs would take effect, but the U.S. plan “may never be imposed” if the two nations agree to a trade deal, says the WSJ. In a bid to temper anxiety among U.S. exporters, Secretary of Commerce Wilbur Ross said China's tariffs "amount to about three-tenths of a percent of our GDP. So, it's hardly a life-threatening activity."