Grand Ayatollah Ali Sistani Issues Fatwah Allowing Armed Resistance Against US Troops

This is rather significant, and I agree with M. Duss his explicit approval of anti-US violance is being driven by the criticism he has invreasingly recieved about his silence regarding the brutality of American tactics.

Juan Cole goes rather deeper into what is going on, and notes that Sistani's relative silence may very well be driven by the consequences of the Shiite uprising in 1920, which had the British putting Sunnis firmly in power as a proxies.

As noted here his Fatwas have seen very limited release, basically face to face with no real record of them otherwise.

If it gets more vocal, not only will US forces have to leave, but it will look like the evacuation of Saigon.