Zeng’s sister, Meixuan Wang, posted on social media that her brother has autism spectrum disorder and a strong fascination with airplanes. She said she does not believe he knowingly worked for Beijing and suggested he may not have understood the seriousness of his actions when border officers questioned him.

Security analysts explain that China’s Ministry of State Security frequently relies on students studying abroad to collect seemingly harmless data, such as aircraft photographs. Michel Juneau‑Katsuya, a former CSIS Asia‑Pacific chief, said people who accept paid tasks for intelligence agencies are called “co‑optees.” By using ordinary students, the agency can obtain useful information while keeping a degree of deniability.

The case highlights how ordinary activities—like taking pictures for a hobby or a small side‑job—can be turned into intelligence‑gathering tools. For overseas students, the line between a harmless interest and a covert assignment can be blurry, making them vulnerable to recruitment by foreign services.