A United States Coast Guard (USCG) Port Security Unit (PSU) boat crew fire blank ammunition from .50 caliber heavy machine gun and M240b medium machine guns mounted on a patrol vessel during training.
Port Security Units are an elite force protection unit that can deploy worldwide in order to provide maritime security at ports and other maritime installations.
PSU's are one of the Deployable Specialized Forces (DSFs) that come under the command of the Coast Guard Deployable Operations Group.