Rihanna is no stranger to violence on camera -- see her "Man Down" video for proof -- but in her first feature film role, she's taking it to a whole new level.The singer stars in "Battleship," the Peter Berg-directed big screen adaptation of the classic board game. She plays a hardened Navy sailor that helps take on the aliens that threaten the future of the world, battling alongside Taylor Kitsch and Liam Neeson, amongst other big name co-stars.She's already famously fit, but to get military ready, Rihanna had to kick it up a few notches.Read More... More on Rihanna