[...]
Fallon was the subject of an article published last week in Esquire magazine that portrayed him as opposed to President Bush's Iran policy. It described Fallon as a lone voice against taking military action to stop the Iranian nuclear program."
[...]
Gates described as "ridiculous" any notion that Fallon's departure signals the United States is planning to go to war with Iran.
Guess that means the U.S. is going to war with Iran.
PS. Here's a fuller account of the circumstances behind his resignation.