The House of Representatives’ Foreign Affairs Committee issued a subpoena to force Zalmay Khalilzad to appear after it complained about being kept in the dark over the negotiating process.
Trump had earlier said that he had called off peace negotiations with the Taliban, and revealed that he had arranged but canceled talks with the Islamist militants at his Camp David presidential retreat.
Khalilzad held nine rounds of talks with the Taliban in Doha, Qatar, saying little in public about the negotiations.
He later said he had reached an agreement in principle with the Taliban in which the United States would pull out troops and the militants would promise to break with Al-Qaeda.
Trump has been eager to end America’s longest war, launched 18 years ago after the September 11 attacks on the United States.