The Trump administration, invoking powers the U.S. hasn’t used in more than a quarter century, began a probe into Chinese aluminum imports that could lead to tariffs. The Commerce Department is taking the unusual step of initiating the case itself, rather than going through the regular route of starting an investigation based on petitions filed by U.S. companies. Shares in Alcoa Corp. and Century Aluminum Co. jumped. The investigation covers imports in common alloy sheet, which totaled more than $600 million last year, and was initiated using authority granted by the Tariff Act of 1930, the Commerce Department said Tuesday in a statement. Earlier this year, the U.S. began looking into limits on aluminum and steel imports on grounds of national security. And in August, the Commerce Department announced the U.S. would seek to impose duties on imports of aluminum foil from China, arguing that state subsidies for the domestic industry unfairly disadvantaged American producers. China’s ministry of commerce didn’t immediately respond to a fax seeking comment. Chinese Shipments The U.S. will import about 425,000 metric tons of common alloy aluminum sheet from China this year, said Jorge Vazquez, the managing director of Austin, Texas-based Harbor Intelligence. This investigation “was logical after the implementation of duties on foil, both countervailing duties and antidumping duties,” he said said Tuesday by phone. “If this happens, it will probably increase significantly the chances of domestic capacity expanding here in the U.S.” That figure would be 1.3 percent of China’s primary aluminum output of 31.9 million tons in 2016. Aluminum prices are up 25 percent this year, helped by China’s crackdown on illegal smelters as well as productions curbs to reduce pollution. Higher domestic prices drove overseas shipments in October to their lowest since February. Tuesday’s announcement is the latest sign the Trump administration plans to crack down on what it sees as China’s efforts to flood global markets with cheap metals. U.S. Commerce Secretary Wilbur Ross has said his department would be more willing to self-initiate trade cases against other countries. President Donald Trump pledged during the election to get tougher on China, complaining that its mercantilist policies contributed to the loss of manufacturing jobs in the U.S. But the Trump administration has so far refrained from following through on that threat. “President Trump made it clear from day one that unfair trade practices will not be tolerated under this administration, and today we take one more step in fulfilling that promise,” Ross said in the statement. Shares Rise Century Aluminum erased an earlier loss and climbed 7.3 percent in New York, the biggest gain since August. Alcoa, which had been down as much as 2 percent, ended the regular session up 3 percent, while downstream aluminum producer Constellium NV rose 1 percent. In April, Trump directed the Commerce Department to investigate whether imports of aluminum threaten America’s national security. In doing so, the president invoked the seldom-used Section 232 of the 1962 Trade Expansion Act, which gives him power to impose tariffs on products that present a security risk. However, Trump has yet to decide whether to take action. Vazquez says he thinks the self-initiated probe will effectively eliminate chances of Trump following through with 232. “I believe that this investigation reduces even further in my view the chances of duties on primary aluminum via Section 232, because its complaints are focused on China,” he said.