China is going after Boeing, America’s biggest exporter, in its trade war with the U.S. Beijing has told Chinese airlines not to place new orders for Boeing jets and is requiring carriers to seek approval before taking delivery of aircraft they have already ordered,

China Southern Airlines Co. suspended the sale of 10 used Boeing Co. 787-8 Dreamliner aircraft, after Beijing’s escalating trade war with the US put supply of aircraft to the mainland at risk.

Shares of Boeing fell Tuesday following a report that China has halted the delivery of all its jets to airlines in the country as part of the escalating trade war.