All fishermen from commercial trawlers to lone amateur anglers are looking to catch “the big one” but some Vietnamese fishermen may have gotten more than they wished for when an 11,000-ton Chinese Navy Jin Class ballistic missile submarine surfaced near their boats. Images from social media have shed some light on this incident that is thought to have occurred in September. Was it a glitch or something else?

The submarine was operating near the Paracel Islands that the Chinese call Xisha. They are at a very strategic position about equal distances from the Vietnam coast and the city of Sanya on the Chinese island of Hainan. Sanya is the submarine’s home base and is known more for being a resort town than a military port.

Vietnam, China and Taiwan all lay claim to the island group and the competing claims have caused turmoil. They are currently controlled by the Chinese so the mere presence of the submarine should not raise any eyebrows of those who observe the movements of large aquatic vessels. The bigger question is: Why did the submarine emerge and let its presence be known to the fishermen?

China has built six Jin Class submarines and they play a vital role in what China calls its “at-sea nuclear deterrent.” The nuclear-powered subs can stay underwater for several months and it is very unusual for such a vessel to surface and risk detection.

If China wants to send a “message” to Vietnam and other countries bordering the South China Sea, it will move a giant oil rig or use the presence of an aircraft carrier to convey the message. Submarines would likely not be used, and this suggests there is another reason for the sub to surface.

File picture of a Chinese navy submarine leaving Qingdao Port in Qingdao of Shandong Province, China. Guang Niu/Pool/Getty Images

One plausible explanation is that the sub could have gotten entangled in the fisherman’s nets in such a manner that required it to emerge from the water. The powerful submarine can literally drag a fishing boat by its nets resulting in a loss of life. This very thing happened in 1990 when a British submarine drove through the nets of a small fishing boat off Scotland. All four-crew died when their boat was pulled underwater.

In 1984, a Soviet submarine became tangled in the nets of a Norwegian fishing trawler. When efforts to free itself while underwater failed, the submarine had to surface. Its mission was exposed to the NATO country, but the move probably saved lives of those on the trawler and perhaps those of its own crew.

So, it is very possible that the captain of the Chinese sub acted likewise and put aside whatever mission he was leading and emerged to prevent dragging some boats underwater and the possible death of the fishermen.

The loss of stealth seems to be a small price to pay for what might have become another international incident to add to the already sullied reputation of China as the “Bully of the South China Sea.”