Shenghua Wen, 41, who was living illegally in the United States after overstaying his student visa, is charged with violating long-standing US sanctions against North Korea.

Wen and unidentified co-conspirators allegedly concealed firearms and ammunition inside shipping containers that were shipped from Long Beach, California through Hong Kong to North Korea.

The Justice Department said law enforcement seized two devices in August at Wen's home that he planned to send to the North -- a chemical threat identification device and a hand-held broadband receiver that detects eavesdropping devices.

In September, law enforcement seized 50,000 rounds of 9mm ammunition that Wen allegedly obtained to send to North Korea, the department said.

Wen also attempted to obtain a civilian plane engine from a US-based broker, it said.

He faces up to 20 years in prison for conspiracy to violate US sanctions laws.