In 2005, NASA discovers an extrasolar planet with conditions similar to Earth. On the chance that it contains intelligent life, NASA transmits a powerful signal from a communications array based in Hawaii. In the Hawaiian Islands, an international naval fleet at Pearl Harbor engages in a dynamic and intense battle against an alien species known as "The Regents". The aliens come to planet Earth on a mission to build a power source in the ocean. Upon their visit, they come in contact with the naval fleet. Alex Hopper is a talented but undisciplined slacker. His brother Stone, a naval Commander, forces Hopper to join the Navy. Hopper becomes a lieutenant on the USS John Paul Jones DDG-53, sister-ship to his brother's command, the USS Sampson DDG-102. Hopper also falls in love with Admiral Shane's daughter, Samantha, and wants to marry her, but is afraid of asking her father's permission, as he doesn't like Hopper. During the RIMPAC opening ceremony, Hopper gets into a brawl with Captain Nagata of the Japanese Maritime Self Defense Force, In charge of JDS Myoko DDG-175. Hopper soon learns that he is to be kicked out of the Navy at the end of RIMPAC. Meanwhile, Samantha accompanies an Army veteran amputee Mick Canales on a hike on Oahu in order to help him adapt to his prosthetic legs. A small fleet of alien ships arrives in response to the NASA signal. One ship collides with an orbital satellite and crashes in Hong Kong, while five others land in the waters near Hawaii. The aliens erect a massive forcefield around the islands, trapping a number of American, Japanese and other sovereignty's warships, including Hopper's ship. USS Sampson launched attacks on the alien fleets under the command of Hopper's brother and gets killed when they blew up the Sampson with no survivors. With the USS Sampson destroyed, Hopper took charge of the USS John Paul Jones as he is the highest rank officer on board.The Myoko opened fire at the alien fleets and suffered the same fate as the USS Sampson. Captain Nagata and some of his crew members are rescued from the waters and assists the Americans in setting up a discreet way to track the aliens using wave-detection buoys. During a night-time battle, the aliens and the Americans exchange pot shots, but Hopper manages to sink two alien ships. They rescued an alien from the water. They discover the aliens are very sensitive to sun light and have to wear filters during the day. Using this knowledge, Hopper attacks another alien ship at dawn, using a sniper rifle with Nagata to breach their cockpit window and blind them with sunlight. Both ships are destroyed in the battle. A group of alien footsoldiers and scientists lands on Oahu and attack the NASA communications array. Samantha and Mick narrowly avoid their detection, and run into a fleeing NASA scientist. Because the aliens' communications ship crashed in Hong Kong, the aliens plan to use the NASA array to signal their home planet to invade Earth. Realizing that a larger invasion might be imminent, Samantha manages to get a radio and warns Hopper of the threat. Having no better options, the surviving crew of the John Paul Jones return to harbor and board the USS Missouri BB-63, a 70-year old decommissioned battleship that has been converted into a museum. With the aid of the museum staff, all elderly war veterans, Hopper manages to put the Missouri out to sea again. With some clever maneuvers, the Missouri destroys the last alien ship and shells the communications array, destroying the aliens and ending the threat of invasion. Back on shore, the crew and Mick all get medals, including a posthumous one to Stone, after the ceremony, Adm. Shane leads Hopper off to discuss his 'Terms of Surrender' over a meal.