An independent leader of a Shiite group in Iraq said the additional 560 U.S. troops heading to Iraq would be a "target" for his supporters.
"They are a target for us," Muqtada Al-Sadr wrote on his official website late Sunday.
The additional troops, approved by Barack Obama, will bring the authorized number of American service members serving in Iraq to 4,657.
Al-Sadr's supporters, who fought against American troops in the years after the 2003 invasion, are among the largest of several government-sanctioned Shiite armed groups battling IS.
On Friday tens of thousands of al-Sadr supporters rallied in central Baghdad.
When John Kerry talks about ISIS being pushed back and "on the run," we must also be aware of Shiite groups like Al-Sadr's who will gladly fill the void.