U.S. President Donald Trump on Monday suggested that Chinese President Xi Jinping may visit the United States “in the not-too-distant future” for talks as economic tensions escalate between the powers.

Trump has slapped 20% levies on all imports from China since taking office in January, faulting Beijing for not halting the flow of chemicals used to make illegal fentanyl, a leading cause of U.S. drug overdose deaths.

Trump has voiced optimism in recent weeks about having a good relationship with Xi. But there has been little sign of progress on a range of issues splitting the nations, from tariffs to Taiwan.

China objects to the tariffs and says it has taken serious action on counter-narcotics. Beijing has imposed a limited set of its own retaliatory trade actions.

“He’ll be coming,” Trump said, “in the not-too-distant future.”

Trump made the comments as an aside during a board meeting at the John F. Kennedy Performing Arts Center in Washington.

The U.S. president has said tariffs are needed to rebalance uneven trade relations with foreign countries and to raise revenue for the government. He has largely rejected investor fears that the levies could slow growth and raise inflation.

The White House did not respond to a request for further comment. The Chinese embassy in Washington did not respond to a request for comment.