South Korea finds itself in the middle of a growing superpower standoff between the United States, its traditional security guarantor, and China, its largest trade partner but also a key ally of North Korea.

The two men -- identified as international students in Busan -- were arrested on Wednesday, charged with injuring the military interests of South Korea and violating the Protection of Military Bases and Installations Act, according to the Busan Metropolitan Police.

It is the first time foreign nationals have been detained on such charges, they said.

"Two Chinese individuals were arrested yesterday for illegally filming a naval base and a US aircraft carrier," an official from the Busan police told AFP.

"A third Chinese individual is also currently being investigated without detention," he added.

South Korean police believe the detained suspects -- one in his 40s and the other in his 30s -- used drones and mobile phones to illegally film the Republic of Korea Fleet Command in Busan, which is responsible for and oversees the South Korean navy's operation and training.

They are also accused of illicitly filming the USS Theodore Roosevelt, a US aircraft carrier docked in the port city for joint operations, and of conducting unauthorised filming on nine occasions between March 2023 and June 2024.

Their most recent activity took place on June 25, 2024, when then-president Yoon Suk Yeol visited the aircraft carrier and met with South Korean and US troops, according to Busan police.

The illegally obtained materials reportedly included 172 photos and 22 video files, some of which were sahred without authorisation on social media platforms including TikTok.

Busan police also said the suspects used drones manufactured by a Chinese company.

The model in question reportedly requires users to register through the company's app before use, during which all data is believed to be transmitted to servers located in China.

Last month, South Korea fined Chinese e-commerce giant Temu nearly $1 million for illegally transferring Korean users' personal information to China and other countries.