Three Chinese nationals were sentenced to prison after pleading guilty to illegally taking photographs of a US navy base in Key West Florida, the Justice Department announced Friday.

Liao Lyuyou, 27, was sentenced to a year in federal prison after being arrested on December 26, 2019 at the Naval Air Station Key West and found with photographs and video footage of buildings and facilities, including "vital military equipment," of the base, according to the US attorney in the Florida southern district.

In a separate case, Zhang Jielun, 25, and Wang Yuhao, 24, were given one-year and nine-month prison sentences respectively for illegally entering and taking pictures of parts of the same base on January 4, including a residential area for navy personnel.

Neither statement gave details on the background of the individuals, nor did they allege they were involved in espionage. But they stressed that the Chinese were not acting as regular tourists in the popular south Florida city.

Liao snuck into one part of the sprawling base by crossing rocks on a waterline to get around a fence. Zhang and Wang rejected a guard's warning to turn their car around and not enter another part of the base. They drove into the area, stopped their car and shot pictures before being detained.