China on Tuesday imposed tariffs on some U.S. imports in a swift response to new U.S. duties on Chinese goods, raising the stakes in a showdown between the world's top two economies even as President Donald Trump offered reprieves to Mexico and Canada.

Lighthizer, who campaigned with President Trump, serves as an unofficial adviser. He was reportedly passed over for Treasury secretary, but he remains close to the president. Lighthizer says U.S. trade with China has largely benefited an adversary who has engaged in stealing trade secrets and other malicious actions.