TAIPEI (Taiwan News) — Two Taiwanese were detained in South Korea on Sunday for illegally filming at a US air base, South Korean police announced on Monday.

The Yonhap News Agency reported that the two suspects are accused of unlawfully photographing US military equipment and installations on Saturday at an air show held at Osan Air Base in Pyeongtaek, about 60 km south of Seoul. The two suspects are male, one in his 40s and the other over 60, per CNA.

Visitors are typically allowed to take photos freely at South Korean air shows. However, recent incidents involving Chinese illegally filming South Korean military facilities prompted the US military to bar citizens from certain countries, including China and Taiwan, from entering the Osan Air Power Days event.

The two suspects reportedly defied the ban and snuck into the air show. The Gyeonggi Nambu Provincial Police Agency said that the Pyeongtaek Police Station detained the two men.

They are being held in emergency detention for breaching South Korea's Protection of Military Bases and Installations Act. Police are currently considering whether to apply to formally place the two suspects under arrest.