U.S. Customs and Border Protection said it recently made an unusual seizure at a port in California.

Agents in Long Beach intercepted three shipments containing nearly 53,000 sights, stocks and other gun parts that came illegally from China.

"There was no attempt to hide the importation," Jaime Ruiz told NPR on Friday. He said the gun parts were correctly labeled and still had their original trademarks. And all three shipments were headed to a legitimate seller and distributor.

"It's kind of an unusual situation," Ruiz said.

CPB stopped the shipments over the past three months and consulted with investigators at the Bureau of Alcohol, Tobacco, Firearms and Explosives. The agency concluded that the cargo breached multiple regulations, including an arms embargo that the United States imposed on China.

The seizure comes at a time when confiscations of gun parts, munitions, explosives and fireworks have increased 18% over last year, across the United States' 328 ports of entry, Ruiz told NPR. But usually smugglers attempt to illegally export weapons and ammunition made in the United States.

"We can't characterize this as a new trend, but something really unusual, as China historically is the main source of other items like wearing apparel, footwear, watches, jewelry, handbags, wallets and electronics," Ruiz said.

The CPB has noted a different trend feeding a black market — the flow of counterfeit computer networking equipment from China. A Homeland Security report found that last year, CPB and Homeland Security Investigations seized 213 shipments containing routers and other equipment sporting fake trademarks, a 25% increase in seizures from 2017. Last year's seizures were valued at nearly $15.5 million.

Phony routers could possibly be linked to the Chinese government, says Will Carter, deputy director at the Center for Strategic and International Studies' Technology Policy Program, "but the bigger concern is that the routers are not properly maintained" by a supplier to patch vulnerabilities. "They can be built with poor-quality components," he told NPR.

In a publicized federal case from 2008, the FBI identified some 3,500 counterfeit network components from China through an effort called Operation Cisco Raider. "Crimes like these threaten international commerce, national security and the very safety of our citizens," a Homeland Security assistant secretary said at the time.

CPB said the recently confiscated shipments of gun parts were worth about $378,225. The seizure led some to wonder whether the items were a test to see how closely the U.S. government was monitoring shipments or a business was just trying to cut corners by buying cheaper parts.

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