Blast (2004)

A terrorist, Michael Kittredge, posing as an environmentalist protester leads a team of highly-skilled mercenaries to take control of an oil rig off the coast of California, intending to detonate an electromagnetic bomb over the United States, striking a sort of "new Pearl Harbor" attack on behalf of enemies to the nation. What Kittredge didn't count on is a tugboat captain, Lamont Dixon, who survives an attack on his ship, and is soon recruited by an FBI agent to infiltrate the oil rig and procure information about their plans... and if possible, stop them. In the process, Dixon meets an eager computer expert aboard the oil rig who helps Dixon even as he gets on his nerves and Lamont suspects he can't really trust him.