The little Tugboat that could.

Naval Logistics employ such assets as tankers, supply ships, dry-docks and tugboats and are generally ignored by "internet warriors." In recent years and without much fanfare, the PLAN has built a number of large ocean-going tugboats to support their enlarged blue-water operations. These new tugboats are geared towards operations outside of the harbor. In addition to towing many PLAN tugboats also perform supply runs to China's offshore garrison (here) and acted as fuel tanker for submarines.

In July 2009, Tugboat 721 took part in a North Sea fleet drill 170 Kilometers SouthWest of Okinawa (here) to perform emergency damage control, search-and-rescue, fire-fighting and other support operations.

For a more complete list of PLAN Tugboats, please visit this CDF thread.
http://www.china-defense.com/smf/index.php?topic=448.0

Tugboat 174 delivering supply to Nansha island garrison

Refueling a Yuan class submarine.