Muslim leaders are trying to strengthen Sunni-Shi'ite ties in the US, hoping to head off conflicts between the faith's two major sects and get American Muslims to focus on common problems. With sectarian divisions fueling violence in Iraq, Sunnis and Shi'ites in the US are increasingly wary of a spillover effect. In one public example, leaders from both traditions have launched "Intra-faith Code of Honor" campaigns in three cities with major Muslim populations. So far, 20 Sunni and Shi'ite leaders in Southern California have signed the first such code. The document denounces "takfir" - the labeling of another Muslim as a nonbeliever - forbids hateful speech about revered figures and urges debates at the scholarly level, not the street level. Similar agreements are expected to be completed this month in Detroit and Washington, D.C.