American Warships (2012) on Netflix

Plot summary

The USS Iowa, the last American battleship, is on its final voyage before it becomes a floating museum. A US plane is shot down over the sea by an unknown attacker, and the army concludes that North Korea is responsible. War looks likely. The true attacker is an alien force, and the captain of the Iowa chases an invisible ship. The aliens' electromagnetic pulse weapons do not affect the battleship's outdated technology, so the old ship becomes the last line of defense. In Washington, D.C., General Hugh McKraken tries to stop the United States and other powers from entering a wider war, while coastal towns in North Korea are also attacked, apparently to push the world into destroying itself. He works to buy time for the Iowa to prove the aliens are real.