Fighting Sadr

A question raised by Matthew Yglesias here caused me to do a google news search and learn that we've detained 25 Sadrites at a Shi'ite mosque in Sadr City. So has there been a policy shift? Is there a crackdown on Sadr because we fear some sort of election turmoil? Does Allawi not want them supporting the United Iraqi Alliance, and we're serving as pawns? This is the sort of thing I'd love to hear more about.