BEIJING: China imposed sanctions on nine US defence firms on Wednesday (Sep 18), the foreign ministry said, describing the measures as retaliation for Washington's approval of military equipment sales to Taiwan this week. " Weapons sales by the United States to China's Taiwan region have seriously violated the one-China principle, ... seriously infringed upon China's sovereignty and security interests, (and) damaged China-US relations," foreign ministry spokesman Lin Jian told a news conference.