U.S. ground forces in Iraq are held hostage to long and vulnerable supply lines up from Kuwait and the Gulf, all controlled by Shiite militias strongly sympathetic to the Islamic republic in neighboring Iran. Iran has quietly and consistently built up its ties to both these groups and to the Iraqi government of Prime Minister Nouri al-Maliki which has developed a mind of its own quite unanticipated by the Bush administration strategists. It is impossible to believe that the White House looked with any kind of approval on Iranian President Mahmoud Ahmadinejad's unprecedented visit to Baghdad as Maliki's guest. Yet the visit went ahead anyway.

The U.S. public and the mainstream media appears unaware of how much the U.S. army's supply lines through southern Iraq are vulnerable to a general Shiite rising, a fact not lost on the professionals in the U.S. armed forces. That explains why three successive commanders of CENTCOM – U.S. Central Command – have flatly opposed launching any major air strikes against the Iranian nuclear facilities while a large contingent off the U.S. ground army is in Iraq: They are: Gen. Anthony Zinni, Gen,. John Abizaid, and most recently, Adm. William "Fox" Fallon. U.S. President George W. Bush has dispensed with the services of them all.

Even Sen. John McCain of Arizona, who currently looks certain to claim the Republican presidential nomination and then run as the heir to his old arch-rival Bush has now publicity opposed launching air strikes on Iran. He made this remarkable position clear in comments on Sunday.

No one has been a stronger hawk on the Iraq war than McCain. Even today, he favors maintaining massive U.S. military force there for the indefinite future. McCain – unlike Bush – recognizes that you cannot have everything at the same time. He recognizes that it is the very presence of such a large U.S. military force in Iraq that rules out major air strikes on Iran as a viable option.

The likelihood of a U.S. air strike on Iran before Bush leaves office remains high, however. Tehran does not appear to be worried by this threat. How else to explain the reckless disregard with which the Iranian government continues to publicize its (possibly exaggerated) progress on the nuclear program.

U.S. policymakers should consider the possibility that Iran may actually want to provoke a U.S .air attack in order to motivate the Shiite militias of southern Iraq to rise up on its behalf and cut U.S. ground supply lines.