China announced retaliatory tariffs on select American imports and an antitrust investigation into Google on Tuesday, just minutes after a sweeping levy on Chinese products imposed by U.S. President Donald Trump took effect.

American tariffs on imports from Canada and Mexico were also set to go into effect Tuesday before Trump agreed to a 30-day pause as the two countries acted to address his concerns about border security and drug trafficking. Trump planned to talk with Chinese President Xi Jinping in the next few days.

This isn’t the first round of tit-for-tat actions between the two countries. China and the U.S. engaged in an escalating trade war in 2018 when Trump repeatedly raised tariffs on Chinese goods and China responded each time.