For Fallon, the perception of a disagreement with Bush's policies on Iran rather than an actual rift was enough reason to step down.

"Recent press reports suggesting a disconnect between my views and the president's policy objectives have become a distraction at a critical time and hamper efforts in the Centcom region," Fallon said in a statement Tuesday in which he announced his resignation as head of U.S. Central Command, arguably the most important in the U.S. military.

Democrats seized on Fallon's resignation as an opportunity to criticize Bush.

"Over the last seven Bush years, we've seen those who toe the company line get rewarded and those who speak inconvenient truths get retired," Sen. John Kerry, D-Mass., said in a written statement.