The Obama administration is expected to launch a formal complaint Thursday against the Chinese government with the World Trade Organization over subsidies it says Beijing provides to the country’s vast aluminum industry, according to people familiar with the matter.

The complaint would represent an escalation of trade disputes between countries with the world’s two largest economies almost a week before Donald Trump assumes the U.S. presidency. Trump suggested again Wednesday in a news conference that trade relations with Beijing would be a top priority, saying the U.S. trade imbalance with China was too large.