Diplomatic efforts to end a standoff between US troops and an anti-American cleric in one of the holiest cities in Shiite Islam pressed forward today and an Iraqi leader said he saw “flexibility” on the side of the charismatic cleric, who heads a militia with several thousand members.

Gunmen assassinated an Iranian diplomat in Baghdad just as Iran, with tacit US approval, attempted to mediate with radical Shiite cleric Muqtada al-Sadr defying American forces in the southern Iraqi city of Najaf.