China has detained a Japanese national on suspicion of being a spy, with Tokyo pressing for his immediate release as ties between the two neighbors continue to sour. But this is far from the first time Beijing has detained a Japanese citizen over alleged espionage. And it may not be the last.

The detention in Beijing earlier this month involved a Japanese man in his 50s who is being held on suspicion of violating China’s notoriously opaque counterespionage law. The Japanese pharmaceutical company Astellas Pharma has confirmed that the man is one of its employees. He had planned to return home this month.

Since China passed its counterespionage law in 2014, 17 Japanese nationals, including the Astellas employee, have been detained in the country for allegedly engaging in spy-related activities, with Beijing ramping up a crackdown on foreign organizations and affiliated individuals, citing national security concerns.