US Navy sailors tend to be overlooked when it comes to Hollywood blockbusters, but the new action movie \"Battleship\" features American destroyers and their crews in the starring role, waging war against hostile aliens in the Pacific Ocean. The Pentagon gave director Peter Berg access to a huge naval exercise and allowed him to film scenes on six ships, including four destroyers, an aircraft carrier and an amphibious assault ship, officials said. Even the retired USS Missouri, known for hosting the surrender of the Japanese in World War II, gets screen time in the film, which opens at the US box office on Friday after debuting abroad in April. Script writers have not taken much interest in naval warfare for decades but US naval recruiters will be ecstatic over scenes from \"Battleship\" with sailors performing heroic deeds on deck in blue camouflage, the new uniform for American surface warfare officers. \"It\'s very much a SWO picture,\" said Philip Strub, who oversees the Pentagon\'s cooperation with the movie industry. The sea power-theme echoes talk by strategists in Washington who now speak of returning to America\'s \"maritime roots,\" as the United States keeps a watchful eye on China\'s growing military and economic might. But aliens -- and not the Chinese -- are the bad guys in \"Battleship.\" And unlike World War II-era movies, \"Battleship\" portrays Japan as a staunch American ally, including a supporting role for a Japanese naval officer. Inspired by the classic board game, \"Battleship\" stars Liam Neeson as Admiral Shane and pop singer Rihanna dons a naval uniform to play the part of Petty Officer Cora \"Weps\" Raikes. She falls under the command of an impulsive young officer named Alex Hopper, played by Taylor Kitsch of NBC\'s \"Friday Night Lights\" fame, who finds himself face-to-face with a powerful alien enemy. Pentagon advisers to the film gave Rihanna high marks for her portrayal of the petty officer, Strub said. \"What I heard from people in the navy is that she does a pretty good job. People say she\'s credible,\" he told AFP. During filming, a naval officer on the set noticed Rihanna failed to wear a regulation T-shirt under her navy uniform, unlike other female sailors standing nearby. The officer told them that would never be allowed on a realwarship. The filmmakers quickly obliged and the pop diva opted for a more modest look, Strub said. Dozens of real sailors also appear in the movie, as well as a wounded Army officer from the Iraq war who lost both his legs in combat. Colonel Greg Gadson plays a veteran recovering in Hawaii from his critical war injuries. To put modern warships on the screen, the film production made the most of aerial shots from a \"Rim of the Pacific\" exercise in 2010, a drill that the US Navy conducts every two years with allies. The USS John Paul Jones, one of several guided missile destroyers in the picture, was filmed in port at San Diego and at sea during a training exercise in August, officials said. Hollywood producers and directors are permitted to film American military hardware for a fee but only after the Pentagon reads a script and approves how military characters are portrayed. The Defense Department weighs whether a film subject offers \"valuable information\" to the public or could help with recruitment, and sometimes goes to great lengths to cooperate with movie projects, such as \"Black Hawk Down.\" The Pentagon turned down a chance to work with the makers of \"The Hurt Locker,\" a film about a bomb disposal team that went on to win six Oscars in 2010, partly because the main character\'s venturing off base was considered unrealistic. Navy leaders apparently have no qualms about the script, as the service\'s civilian chief, Navy Secretary Ray Mabus, appears in the film as the skipper of the aircraft carrier USS Ronald Reagan.