The seized items included gun sights, stocks, muzzles and other parts worth a total of more than $378,000. The parts were intercepted in recent weeks, according to law enforcement sources familiar with the matter, and were packed in their own cargo containers on three separate ships that were also carrying household items, apparel, toys, industrial machinery and other imports.

Customs and Border Protection officers seized the shipments and consulted ATF agents, who confirmed that the firearm parts violated an embargo against Chinese weapons.

"This interception underscores the successful collaboration between CBP officers, import specialists and ATF investigators," said LaFonda Sutton-Burke, CBP port director of the L.A./Long Beach Seaport.