In a video just over four minutes long shot from the bridge of the destroyer USS Hopper, the small boats can be seen racing near the wake of 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. I intend no harm. Over."
Often uneven and shaky, the video condenses what US navy officials have said was a 20-minute confrontation early on Sunday between three navy warships and five Iranian fast boats.
'You will explode'
It ends with a blank screen, as only the audio of the navy's final warning can be heard, just after the voice apparently from one of the small boats warns that "I am coming to you".
"Inbound small craft: You are approaching a coalition warship operating in international waters. Your identity in unknown; your intentions are unclear," the unidentified US navy crew member says.
He then cautions the Iranians that if they do no steer clear they will be "subject to defensive measures".
"Request that you alter course immediately to remain clear," the crew member says.
After a pause, the voice over the radio issues a final threat: "You will explode after [indecipherable] minutes."
A navy crew member then repeats the threat he has heard, saying: "You will explode after a few minutes?"
The incident was denounced by George Bush, the US president, on Tuesday as a "provocative act".
|The videotape filmed was from the destroyer |
USS Hopper [File: EPA]
Calling it a "dangerous situation", Bush said: "They should not have done it, pure and simple. ... I don't know what their thinking was, but I'm telling you what my thinking was: I think it was a provocative act."
The audio and video recordings were made separately, but were pulled together by the navy.
But US military officials, including Vice-Admiral Kevin Cosgriff, the top US navy commander in the Gulf, cautioned that they had not been able to definitively connect the radio call with one of the Revolutionary Guards boats.
Commander Lydia Robertson, a spokeswoman for the 5th Fleet, said "the ships were close enough to shore that the call could have come from a shore station, it could have come from another boat".
"But the call did happen while the small boats were there," she added.
Cosgriff said the navy convoy passed near but outside Iranian waters and the Iranian boats "manoeuvred aggressively" before fleeing as the American ship commanders were preparing to open fire.
In Tehran, Iran's foreign ministry played down the incident as routine and suggested the boats had not recognised the US vessels.
"That is something normal that takes place every now and then for each party," Mohammed Ali Hosseini, a spokesman, told the state news agency Irna.
But Cosgriff said Iran's "provocative" actions were "deadly serious" to the US military.
Ali Reza Tangsiri, a senior Revolutionary Guards commander, said Iran had the right to ask any ships to identify themselves upon entering or leaving the sensitive waterway.
|Vital oil traffic passes through |
the Strait of Hormuz
And the Revolutionary Guards said their boats never threatened the US vessels during the encounter, only asking them to identify themselves then letting them continue into the Gulf.
But Cosgriff, the commander of the US 5th Fleet, which patrols the Gulf and is based in nearby Bahrain, said the American vessels had already been identified by Iranian authorities earlier in the day before the confrontation occurred.
The US commander also pointed out that the American ships were clearly marked and the incident took place during the day when they could be seen.
"I can't help but conclude that it was provocative," he said.
The flare-up of US-Iranian tensions comes as Bush prepared to leave on Tuesday evening on an eight-day Middle East trip designed in part to counter Iran's influence in the region.
Many Arab countries fear the Iranian-American rivalry could erupt into a military confrontation that would put them in the crossfire and hurt vital Gulf oil traffic through the Strait of Hormuz.