Yinpiao Zhou, 39, was arrested as he readied to board a flight to China from San Francisco, authorities said.

"This defendant allegedly flew a drone over a military base and took photos of the base's layout, which is against the law," United States Attorney Martin Estrada said.

"The security of our nation is of paramount importance and my office will continue to promote the safety of our nation's military personnel and facilities."

Chinese foreign ministry spokeswoman Mao Ning said she was "not aware of the situation" when asked about the case at a regular press briefing on Thursday.

Charging documents say detection systems at Vandenberg tracked a drone as it flew about a mile (1.6 kilometers) above the facility in late November.

Security personnel at the base, which is the launch site for space missions -- including Elon Musk's SpaceX Falcon 9 rockets -- as well as missile tests, traced the drone to a nearby public park where they allegedly found Zhou with the device concealed in his jacket.

Agents who acquired a search warrant examined the drone, which contained aerial photographs of the base.

The Justice Department said Zhou is a Chinese citizen and a lawful permanent resident of the United States, and had been in China most recently in February.

Zhou did not enter a plea when he appeared in a San Francisco court on Tuesday charged with failure to register an aircraft not providing transportation and violation of national defense airspace.

He is expected to appear in US District Court in Los Angeles in the coming weeks.

Zhou remains in custody pending an appeal by prosecutors against the court's decision to free him on bail.

The episode comes less than two years after a national security incident that dramatically raised tensions between Washington and Beijing.

In early 2023 the United States discovered and tracked what it called a spy balloon as it flew high above sensitive US military installations, shot it down and retrieved its large payload of electronics.

The incident prompted concerns China was scooping up vital intelligence, while Beijing said it was a civilian airship blown off-course.