The incomparable Amir Taheri writes:

Watching a second American battle group sail into the Gulf of Oman the other day, one could not help recall the days of gunboat diplomacy. …
On the one hand, US officials, including President George W Bush, claim that Tehran is arming Iraqi insurgents who kill GIs. On the other, it is implied that unless there is Perry Mason style evidence, no action would be taken against Tehran.
Then there is the controversy over Iran’s alleged plans to build a nuclear arsenal. We are told that a Khomeinist regime armed with the bomb would be “intolerable”. But it is never clear at what point the red line is reached.
So far, the natives, watching the gunboats’ ballet on television, have reacted with a mixture of boredom and derision. …
In the old times, gunboat diplomacy worked because the man who sent the flotilla could use it without being second-guessed at every step. The gunboat was a symbol of power that was real because those who possessed it had the will and the courage to use it. In most cases, it was not actually used because those targeted knew that it could be used.
Today, however, the US has all the power in the world but lacks the will and courage to use it. …
Ahmadinejad, reported to watch a lot of CNN, has seen the gunboats sail in. But he has also seen Nancy Pelosi, Jack Murtha, Barrack Obama, and other American luminaries such as Michael Moore, Noam Chomsky and Jane Fonda who would rather see Bush destroyed than the mullahs restrained.

More here.