The Karbala attack and the IRGC

The American Forces Information Service provides the details of the attack in Karbala. Based on the sophisticated nature of the raid, as well as the response, or cryptic non-responses, from multiple military and intelligence sources, this raid appears to have been directed and executed by the Qods Force branch of the Iranian Republican Guard Corps. My sources agreed this is far to sophisticated an operation for the Mahdi Army or Badr Corps, while al-Qaeda in Iraq would have a difficult time mounting such an operation in the Shia south. "The Karbala Government Center raid the other day was a little too professional for JAM [Jaish al-Mahdi, or the Mahdi Army]," according to a military source.

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The Karbala raid makes sense in light of the U.S. raids on the Iranian diplomatic missions in Baghdad and Irbil, where Iranian Qods Force agents were captured, along with documentation that divulged Iran's involvement with and support of Shia death squads, the Sunni insurgent, and al-Qaeda in Iraq and Ansar al-Sunnah. Five Iranians from the Irbil raid are still in U.S. custody, and captured U.S. soldiers would provide for excellent bargaining chips
An implied task of every military operation is to gain intelligence. I am willing to bet the decision to take the laptop (If one was taken) and the captives was made by the raid leader on the ground. However, when the raid party got to its rally point, a more senior leader was present and he gave the order to keep the laptop and leave the Soldiers.

I doubt a laptop was the sole target of this attack. I think the raid was undertaken because the occupants inside were being effective in their AO. Additionally, part of the "clear and hold" plan is to create Joint Security Stations (JSS) that are significantly smaller than many FOBs that currently exist in Iraq. This attack may have been a "proof of concept" for future attacks on the JSSes. Finally, this was also a considerable propaganda victory for the attackers.