China's newest nuclear-powered submarine has sunk, but not recently. It sank months ago in the spring. The cause of the sinking is not clear. When asked, Beijing feigned ignorance. A Chinese Foreign Ministry spokesperson said he was unfamiliar with the topic, but Beijing's response is not surprising. After all, this is a major setback for China, which has been trying to expand its naval prowess. Still, the mysterious sinking of China's nuclear submarine raises several serious questions. Why is China trying to conceal the cause of the sinking? Was the submarine carrying nuclear fuel at the time of the sinking? Why is China tight-lipped about potential nuclear risks?