On June 4, the U.S. Navy announced its plans to rotate four Arleigh Burke-class destroyers currently forward deployed in Rota, Spain. The USS Donald Cook (DDG-75), USS Ross (DDG-71), USS Porter (DDG-78), and USS Carney (DDG-64) will likely be replaced with Aegis ships featuring the newer Baseline 9 combat system. The Navy also plans to relocate a helicopter maritime strike squadron (HSM) to the area. The rotation is set to start in 2020 and continue to 2022.