The Chinese government imposed sanctions on 20 U.S. defense companies and 10 of their executives on Friday in retaliation for the Trump administration’s approval of a large package of weapons for sale to Taiwan.

The targets include Northrop Grumman, Boeing’s St. Louis-based defense unit and Palmer Luckey, founder of Anduril Industries. Preparing for a potential conflict with China has been a major focus for Luckey and his startup, which owns three of the sanctioned companies.

Read more: China Sanctions 20 US Companies Over Taiwan Arms Sale