A commercial satellite image shared on social media appears to show a Chinese submarine entering an underground base off the island of Hainan in the South China Sea.
The photo, first posted online by Radio Free Asia, shows a Chinese Type 093 Shang-class nuclear-powered fast-attack submarine at Yulin Naval Base, the War Zone reported this week.
The base is one of China’s key facilities to protect its naval assets.
Carl Schuster, former director of operations at U.S. Pacific Command’s Joint Intelligence Center, told CNN the tunnels at Yulin also make it difficult for an adversary to observe Chinese military operations and intentions.
“You have no evidence of [the submarine’s] combat readiness, operational response times and availability,” he said. “Tunnels blind potential opponents to the submarines’ operating status and patterns, denying them the ability to determine the state of China’s military preparations, knowledge critical to assessing China’s intentions and plans.”
Other experts told CNN it is rare for a satellite to catch such a moment, but it is not rare for China to use underground military bases.
“The Chinese have tremendous experience building underground facilities,” Drew Thompson, a former Pentagon official, told CNN. “It’s in keeping with their strategic culture.”