In a statement read at Friday prayers in mosques across Iraq, Muqtada al-Sadr extended support to Iraq's police and soldiers, as long as they don't fight alongside American forces.
Al-Sadr, who is based in Iran, did not elaborate. But one of the anti-U.S. cleric's core goals is ending the U.S. presence in Iraq.
About 50,000 U.S. soldiers remain in Iraq, primarily training Iraqi security forces and helping track down and fight extremists, although U.S. officials say the American combat mission has formally ended.
Al-Sadr's Mahdi militia battled U.S. forces in two major uprisings.