Gray Zone Tactics Playbook: Over-the-Horizon Hiding
Over-the-horizon hiding is a simple tactic used by gray zone vessels to evade detection or public exposure. Ships can conceal their presence by relocating their vessels just beyond the earth's curvature—typically about 12-24 nautical miles away, depending on weather conditions and the elevation of the observing sensor.
Hiding can also shield a vessel from being picked up by most basic radar systems. When coupled with the "going dark" tactic of deactivating a vessel's Automatic Identification System (AIS) broadcast, it becomes hard to detect.
However, by March 14th, dozens of Chinese vessels had returned to the reefs around Thitu Island and re-enabled their AIS transponders.
The most likely explanation for this peculiar behavior is that the militia ships wanted to avoid being caught on camera. The Philippine government had at the time just launched its new transparency initiative and had begun publishing photos of the vessel swarm off Thitu.
The maritime militia continued the practice of scattering its ships around Thitu Island until it moved most of them further south in the summer of 2023.