Two towboats attached to a naval submarine flotilla under the PLA Northern Theater Command tow a submarine to bear off a port during a training exercise recently in waters of the Yellow Sea. Photo: China Military

A submarine attached to a naval submarine flotilla under the PLA Northern Theater Command steams in the sea during a training exercise recently in waters of the Yellow Sea. Photo: China Military

A submarine attached to a naval submarine flotilla under the PLA Northern Theater Command steams in the sea during a training exercise recently in waters of the Yellow Sea. Photo: China Military

A submarine attached to a naval submarine flotilla under the PLA Northern Theater Command steams in the sea during a training exercise recently in waters of the Yellow Sea. Photo: China Military

A submarine attached to a naval submarine flotilla under the PLA Northern Theater Command steams in the sea during a training exercise recently in waters of the Yellow Sea. Photo: China Military