President Trump’s statements against the World Trade Organization hurt America first. The president is no friend to the global trade body, which is hunkering down for its biennial confab. Reforms are needed, but America has won most of the complaints it has brought to the global trade body, including against China.

Mr. Trump’s trade chief, Robert E. Lighthizer, will emphasize national sovereignty over multilateralism at meetings in Buenos Aires this week. His push for W.T.O. reforms and fair trade policies has tamped down expectations for this year’s gathering, when reducing agricultural subsidies is on the agenda. During his presidential campaign, Mr. Trump threatened to pull the United States out of the W.T.O., and he has repeatedly said the country has been treated unfairly.

Yet the United States, the most frequent W.T.O. complainant, has won more than 90 percent of its cases over the last 20 years. China has been a frequent target. In 2015, China eliminated quotas for rare earths used in mobile phones after the organization declared the system violated trade policies. The United States followed up with a complaint against Chinese quotas on raw materials used in the steel and auto industries.

The Trump administration is also undermining the organization’s dispute-settlement system by blocking the appointment of new judges for its seven-member appellate body. With another judge’s term ending this month, the panel will go down to four members, with three of them needed to decide cases. That could slow down United States cases, such as a complaint on Chinese quotas on wheat, rice and corn advocated by American farmers.