President-elect Donald Trump on Tuesday chose trade lawyer Jamieson Greer as his new U.S. trade representative, elevating a key veteran of his first-term trade war against China to execute a sweeping tariff agenda that promises to upend global trade.

The lawyer Jamieson Greer is set to be the top U.S. trade negotiator, a crucial position given the president-elect’s threats to impose tariffs on imports from other countries.

Lighthizer and Greer worked together at the Skadden Arps law firm before Trump was first elected in 2016. After Lighthizer was confirmed as U.S. trade representative by the Senate, he brought in his much younger colleague to be his chief of staff.