A leaked U.S. military assessment says the Chinese military may soon deploy a high-altitude spy drone that travels at least three times the speed of sound, the Washington Post reported late on Tuesday.

The newspaper cited a secret document from the National Geospatial-Intelligence Agency.

The document, which Reuters could not confirm or verify independently, features satellite imagery dated Aug 9 that shows two WZ-8 rocket-propelled reconnaissance drones at an air base in eastern China, about 350 miles (560km) inland from Shanghai, according to the newspaper.

The U.S. assessment said China's People's Liberation Army (PLA) had "almost certainly" established its first unmanned aerial vehicle unit at the base, which falls under the Eastern Theater Command, the branch of the Chinese military responsible for enforcing Chinese sovereignty claims over Taiwan, the newspaper reported.

The U.S. Defense Department did not immediately respond to a request for comment. The Chinese government could not immediately be reached for comment.

The Washington Post said it obtained the assessment of the program from a trove of images of classified files posted on the Discord messaging app, allegedly by a member of the Massachusetts Air National Guard, who was arrested last week.

The FBI on Thursday arrested Jack Douglas Teixeira, a 21-year-old member of the U.S. Air National Guard, over the leaks online of classified documents that embarrassed Washington with allies around the world.

The leaks first became widely known earlier this month, setting Washington on edge about the damage they may have caused. The episode embarrassed the U.S. by revealing its spying on allies and purported Ukrainian military vulnerabilities.

Taiwan president Tsai Ing-wen's recent meeting with U.S. House of Representative Kevin McCarthy had upset Beijing. China, which claims democratically ruled Taiwan is one of its provinces, says Taiwan is the single most important and sensitive issue in its relations with the United States. Taiwan's government rejects Beijing's sovereignty claims.

(Reuters)

The Pentagon building is seen in Arlington, Virginia, U.S. (Reuters)

Leaked US assessment says China readying supersonic spy drone unit: Washington Post