Jack Ma, the co-founder of Alibaba Group Holding Ltd. and China’s richest man, gave a dire warning that the escalating trade war with the U.S. is going to be severe and long-lived.

“It’s going to destroy not only China-U.S. trade, it will destroy a lot of small businesses,” Ma said during a speech at the World Trade Organization on Tuesday. “This thing may last for 20 years, unfortunately.”

Ma spoke at the WTO as the Geneva-based organization has come under threat from Donald Trump’s efforts to recast the international trading system in a way that he says will be more balanced to the U.S. The American president has targeted allies and adversaries alike, threatening tariffs on all of China’s exports, proposing levies on European car-makers and saying he would leave the WTO, which he has described as “unfair.”

Members of the rules-making body, including the European Union and Canada, are pushing plans to reform the WTO, which they say is encumbered by outdated regulations, an anemic negotiating agenda and a broken dispute settlement system.