China's top counterespionage agency announced on Tuesday a case involving a veteran who was arrested on suspicion of colluding with foreign espionage and intelligence agencies to steal Chinese military secrets.

The Ministry of State Security said in a release that military security is crucial to national security, and military-related information is highly sensitive, making it a prime target for foreign spies.

The ministry said authorities recently discovered a domestic social media account, "Winter Night", that was in frequent contact with foreign espionage personnel. The account repeatedly transmitted photos and videos containing information about troop deployments, weapon configurations and military camp environments in a Chinese border area.

The investigation revealed the phone number linked to the account belonged to an elderly person in their 80s living hundreds of kilometers away, who was incapable of committing the crime. This indicated the actual user was someone else, the ministry said.

State security officers analyzed vast amounts of data and eventually identified the suspect, surnamed Ni, after many setbacks in the investigation.

Ni served in the military for two years but was discharged early due to disciplinary problems. The ministry said he possessed some countersurveillance skills and was secretive, making his capture difficult.

When the investigation stalled, officers intercepted a directive from the foreign espionage agency instructing Ni to steal secrets from a specific military base.

The base was located far from urban areas, with complex terrain. It was also winter, and heavy snow often blocked roads.

Despite the harsh conditions, officers set up an ambush around the base. After several days of waiting, they spotted a figure who appeared to be surveying the area before taking out equipment to film. Officers moved in and apprehended Ni.

The Ministry of State Security said the capture operation lasted seven days and six nights. The ministry did not identify the foreign agencies involved.