This guy is definitely suspicious because what tourist to Korea immediately to the Heolleung and Illeung Royal Tombs after arriving at the airport?:

– A Chinese man was released from police custody after being questioned on suspicion of filming the headquarters of the state spy agency using a drone, police said Monday.
The Chinese national in his 40s was released late Sunday, a day after he was caught by the police for appearing to film the National Intelligence Service (NIS) headquarters in southern Seoul in violation of the Aviation Safety Act.
Police said the man appeared to have filmed the NIS building while taking drone footage of the nearby Heolleung and Illeung Royal Tombs, the historical burial grounds of the Joseon Dynasty (1392-1910). (………..)
The man reportedly told police he was trying to film the royal tombs out of a deep interest in world heritage sites, with plans to film temples and other places in the country as well.
The man was also found to have headed straight to the tombs in a rented car after entering the country through Incheon International Airport on Saturday.
You can read more at the link, but they need to make example of this guy to send a message to anyone flying drones illegally.