"VERTREP" and "UNREP" are methods of supplying ships at sea, and they are dangerous and intense processes.
“UNREP,” short for “underway replenishment,” is the term used to describe the transfer of fuel, food, ammunition, repair or replacement parts, people, and mail from supply ships to combatants like frigates, destroyers, and aircraft carriers. "VERTREP," short for "vertical replenishment," supplies ships via back-and-forth flights with helicopters. Both of these methods for supplying ships are dangerous but necessary.
EDITOR'S NOTE: This video was originally published on July 12, 2017.