An Assault Amphibious Vehicle rolls off the USNS Sergeant William R. Button, a prepositioning ship that transported more than 130 pieces of vehicles and cargo to Rota, Spain, for Marines to support Exercise Trident Juncture 15, Oct. 21. The exercise is NATO’s largest since 2002 and will include more than 30 nations participating. - An Assault Amphibious Vehicle rolls off the USNS Sergeant William R. Button, a prepositioning ship that transported more than 130 pieces of vehicles and cargo to Rota, Spain, for Marines to support Exercise Trident Juncture 15, Oct. 21. The exercise is NATO’s largest since 2002 and will include more than 30 nations participating.