Why the Patriot?

The Decider said:

Succeeding in Iraq also requires defending its territorial integrity – and stabilizing the region in the face of the extremist challenge. This begins with addressing Iran and Syria. These two regimes are allowing terrorists and insurgents to use their territory to move in and out of Iraq. Iran is providing material support for attacks on American troops. We will disrupt the attacks on our forces. We will interrupt the flow of support from Iran and Syria. And we will seek out and destroy the networks providing advanced weaponry and training to our enemies in Iraq.

We are also taking other steps to bolster the security of Iraq and protect American interests in the Middle East. I recently ordered the deployment of an additional carrier strike group to the region. We will expand intelligence sharing – and deploy Patriot air defense systems to reassure our friends and allies. We will work with the governments of Turkey and Iraq to help them resolve problems along their border. And we will work with others to prevent Iran from gaining nuclear weapons and dominating the region.

This sticks out like a sore thumb.

I don't think there's any plausible need for a Patriot system -- which tends to counter "tactical ballistic missiles, cruise missiles and advanced aircraft" -- to keep the insurgency (even an Iranian-supported one) or "terrorists" in check. Patriots aren't going to be terribly useful counteracting car bombs, mortars, RPGs, and small-arms fire.

I could imagine, however, that having Patriots deployed around Iraq (or with "allies" elsewhere in the region) would be pretty useful as a defensive option for any retaliation from Iran or Syria if/when either is attacked.