CNN is reporting that, according to U.S. officials, "5 Iranian Revolutionary Guard boats harassed, provoked 3 U.S. Navy warships in the Strait of Hormuz on Saturday." There's no story yet, but I think it's a safe bet that hardliners in the Guard are seeking to create an incident on the eve of U.S. President George W. Bush's visit to the region. Why would they do that? Well, it makes for good distraction from their sinking popularity ahead of March's legislative elections. It forestalls the admittedly dim prospects of a U.S.-Iran rapprochement. It complicates Bush's efforts to buck up the United States' Arab allies (though depending on how they react to this news, it may simplify his mission). And as an added bonus, it'll probably send oil prices upwards for a short while. We can't exclude the possibility that some Guard higher-ups are speculating in the oil markets and turning a tidy profit from these sorts of incidents.
UPDATE: Reuters has more:
A radio transmission from one of the Iranian ships said, "I am coming at you. You will explode in a couple of minutes," CNN reported, citing a U.S. official.
Much more here from Mike Nizza at the NYT's Lede blog.
UPDATE2: Iran's Foreign Ministry is playing down this encounter:
That is something normal that takes place every now and then for each party, and it (the problem) is settled after identification of the two parties," he told the state news agency IRNA.
The incident was "similar to past ones" that were resolved "once the two sides recognized each other."
As blogger "Cernig" notes, this explanation doesn't pass the smell test, but it does indicate that the provocation was not official Iranian policy.