The alleged incident took place at Naval Air Station Key West.

US NAVY PHOTO/Danette Baso Silvers

Authorities arrested a Chinese national Thursday for taking pictures of a restricted area at a US Navy installation in Key West, Florida. The case mirrors a near-identical incident that occurred last December, in which a Chinese student was caught capturing images of buildings and antenna arrays at the same base.

The base, Naval Air Station Key West, is home to the Joint Interagency Task Force South, which monitors illicit trafficking in the air and at sea.

Shortly before 7am on Dec. 26, witnesses saw a man identified in court filings as Lyuyou Liao walking along the secure fence line of the Naval Air Station Key West, according to a complaint filed in federal court. He allegedly entered a restricted area by rounding the perimeter fence and walking across an outcropping of rocks at the water’s edge.

The fence bore “numerous warnings” advising passersby not to trespass on the property, the complaint says. Witnesses nearby say they told Liao not to enter the base, after which they “observed [him] enter the area anyway…and take several photographs.”

Several minutes later, military police arrived and questioned Liao, who claimed he was “trying to take photographs of the sunrise.” Liao was detained and subsequently arrested by agents with the Naval Criminal Investigative Service (NCIS).

In addition to a federal charge of Entering Military, Naval or Coast Guard Property for the Purpose of Taking Photographs of Defense Installations, Liao is also facing state-level charges of criminal trespass.

Noel Clay, a State Department spokesman, declined to comment. The Navy did not immediately respond to a request for comment.

Liao’s arrest bears all the hallmarks of an ongoing espionage campaign by the Chinese, said Cedric Leighton, a retired US Air Force colonel and intelligence officer.

“For example, we know that China often employs ‘runway watchers or ‘airplane spotters’ to monitor takeoffs and landings at US air bases,” Leighton told Quartz. “When I was stationed on Guam we knew that Chinese were monitoring our flight activity at Andersen AFB.”

While Liao’s attempt at accessing Naval Air Station Key West may not have been particularly sophisticated, it “showcases Chinese persistence in going after sensitive targets,” Leighton said. “They will employ both technical and human intelligence to gain as detailed a picture of US military operations as possible.”

This fall, two Chinese diplomats were expelled by the US government after they drove onto a sensitive military base in Virginia that houses a Special Operations unit. The men, who were with their wives, attempted to flee security personnel pursuing them, finally stopping when they were boxed in by fire trucks blocking the road. Authorities reportedly believe one of the men was in fact a Chinese intelligence officer under diplomatic cover.

China has stepped up its espionage activities against the United States in recent years, and constitutes the most severe intelligence threat to the nation, American officials say. In September, authorities charged a Chinese-born US citizen working as a tour guide in San Francisco with being a Chinese government agent, allegedly passing US secrets to China’s Ministry of State Security.

“This is a good reminder that the US remains the top intelligence target for most every country on Earth,” former CIA officer John Sipher told Quartz at the time. “The Chinese are intent on stealing our government and industry secrets, and they are willing to suborn US citizens to do their bidding.”

Liao does not have an attorney listed in court records, and was unable to be reached. He is due in court for an initial hearing later today.