Why is the arrest of a Chinese national on domestic espionage charges significant?

The arrest of a Chinese national on domestic espionage charges is significant because such cases are extremely rare in China. While China has frequently publicized numerous cases of alleged espionage by foreign countries, the arrest of Chinese nationals on charges of spying domestically is unusual. This case involving an ex-soldier who allegedly leaked sensitive military information highlights an uncommon occurrence in China's national security landscape. The rarity of such domestic espionage cases makes this particular arrest noteworthy in contrast to China's usual focus on foreign espionage threats.