Small Iranian fast boats swarmed around US warships in the Gulf, and a heavily accented voice threatened, "I am coming to you. ... You will explode after ... minutes," according to a video released by the Defense Department on Tuesday. The Iranian boats appeared to ignore repeated warnings from the US ships, including horn blasts and radio transmissions. In a four-minute, 20-second video, shot from the bridge of the destroyer USS Hopper, the small boats - including a bright blue one - can be seen racing near the wake the US ships and crossing close to each other. From the Hopper's bridge, after spotting the approaching Iranian boats, a Navy crew member says over the radio: "This is coalition warship. I am engaged in transit passage in accordance with international law. Intend no harm." Often uneven and shaky, the video condenses what Navy officials have said was a 20-minute or so clash. It ends with a blank screen, as only the audio of the US Navy's final warning can be heard, just after the voice warns that they are coming.