170220-N-KP948-039 MEDITERRANEAN SEA (Feb. 20, 2017) Sonar Technician (Surface) 3rd Class Ashley Perna activates a sonobouy during an undersea warfare evolution aboard the Arleigh Burke-class guided-missile destroyer USS Donald Cook (DDG 75). The ship is forward-deployed to Rota, Spain, conducting naval operations in the U.S. 6th Fleet area of operations in support of U.S. national security interests in Europe and Africa. (U.S. Navy photo by Mass Communication Specialist 3rd Class Alyssa Weeks/Released)