Public getting unusual glimpse into one of the military's most closely guarded branches

The public got a rare glimpse into one of the most secret branches of China's military forces on Sunday when the People's Liberation Army Navy released a video of the training and exercises of its nuclear submarine force.

The video, called Things About the PLA Navy's Nuclear Submarines, shows crew members taking an oath while standing atop the nuclear-powered ballistic missile submarine, officers operating equipment within submarines as well as a submarine firing a torpedo.

The force's attack and ballistic missile submarines are shown sailing on the surface or taking part in a naval parade.