China's steel mills, a target of U.S. President Donald Trump's ire, are their industry's 800-pound gorilla: They supply half of world output, so every move they make has a global impact. The steel industry swelled over the past decade to support a history-making Chinese construction boom. Once that tailed off, the country was left with a glut of half-idle, money-losing mills.

Beijing has closed mills and eliminated 1 million jobs but is moving too gradually to defuse American and European anger at a flood of low-cost exports that is double the volume of second-place Japan. Trump responded last week with a blanket tariff hike on steel and aluminum, another metal China's trading partners complain it oversupplies.

Chinese authorities say they shut down 30 million tons of steel production capacity last year. That cut alone is equal in size to the annual output of the No. 9 producer, Brazil, but only a sliver of China's 800 million tons. Beijing's goal is to make its industry more efficient and profitable, not just smaller. So while some mills close, bigger rivals step up production and could become even more formidable global competitors. Beijing has announced plans to shrink steel and coal but has yet to outline plans for others.