MICHELE NORRIS, host:
The tenuous relationship between the U.S. and Iran has been even more strained this week. At issue are conflicting accounts about an incident that occurred Sunday morning between U.S. and Iranian naval vessels in the Strait of Hormuz. The U.S. and Iran have both released videos of that incident, and each blames the other.
NPR's Tom Bowman reports from the Pentagon.
TOM BOWMAN: Last Sunday's incident first set off a war of words. Now, we have a war of competing images. Both sides agree only on these facts: U.S. Navy ships were passing through the Persian Gulf when they were approached by Iranian fast boats.
Let's begin with the U.S. Navy's version of events. It released a video on Monday. It showed the Iranian boats darting around the warships. An American sailor is pictured on the bridge, radios crack a warning to the Iranian boats. A warning whistle is blown. Then the Americans pick up this ominous message.
Unidentified Man #1: I am coming to you. You will explode after minutes.
BOWMAN: I am coming to you. You will explode after minutes. The Pentagon called the Iranian behavior provocative. But U.S. officials concede they can't pinpoint the source of that radio message. They said it could have come from the Iranian fast boats, another ship, even a shore station.
Admiral MIKE MULLEN (Chairman, Joint Chiefs of Staff): I can't shed any light as far as the radio transmission is concerned.
BOWMAN: That's Admiral Mike Mullen, the chairman of the Joint Chiefs of Staff. He said today the incident may signal a new, more aggressive strategy by Tehran in the Gulf.
Secretary ROBERT GATES (U.S. Defense Department): What concerned us was, first, the fact that there were five of these boats.
BOWMAN: That's Defense Secretary Robert Gates speaking yesterday.
Sec. GATES: And the second that they came as close as they did to our ships and behaved in what appeared to be a pretty aggressive manner.
BOWMAN: Now, let's consider the Iranian version of events. The foreign ministry in Monday said the incident was routine, normal. On Wednesday, they called the American video a fabrication. Yesterday, they released their own video on Iran's English-language satellite channel, Press TV.
Unidentified Man #2: (Speaks in foreign language).
BOWMAN: The Iranian picture show no hint of confrontation. The video shows an Iranian Revolutionary Guard sailor standing on a small boat, radioing the Americans and receiving a standard reply.
Unidentified Man #3: This is coalition warship 73. I am operating in international waters.
BOWMAN: Responding to the Iranian charges of fabrication, Defense Secretary Gates dismissed them, saying, who you are going to believe? U.S.-Iranian tensions in the Gulf go back years.
Harlan Ullman is a retired Navy officer who commanded a ship in the Gulf during the 1980s. He believes the American tape is real, but he's also not ready to say the Iranian tape is fabricated.
Mr. HARLAN ULLMAN (Retired U.S. Naval Commander): Until we have a chance to analyze the Iranian one I think that we should withhold our judgment.
BOWMAN: And Ullman says there are ways to check the authenticity of the Iranian tape, such as matching Iranian radio transmissions with those recorded by the Americans. Ullman agrees with American officials that whatever happened in the Strait of Hormuz, it's a serious event, one that both sides should try to avoid. When similar confrontations occurred with the Soviet navy during the Cold War, Ullman says both sides signed an agreement to prevent incidents at sea.
Mr. ULLMAN: So that inadvertently, there would not be a mistake or an error that could get out of hand.
BOWMAN: Ullman says the U.S. and Iran should work out a similar agreement. That might help. Today, the Navy announced that one of its ships fired warning shots last month at a small Iranian boat in the Strait of Hormuz.
Tom Bowman. NPR News, the Pentagon.