Tens of thousands of followers of a Shiite anti-American cleric are rallying in Baghdad, demanding the US military leave Iraq at the end of the year.
Thursday's demonstration by Muqtada al-Sadr's supporters comes as Iraqi leaders weigh whether they should ask the US troops to stay on.
Washington is pushing Baghdad for a quick decision on whether to keep some of the 46,000 soldiers currently in Iraq beyond a Dec 31 departure deadline to ensure security.
The US military counted about 300 busloads of people from Iraq's Shiite south converging on eastern Baghdad's Sadr City for the demonstration.
US, Israeli and British flags are painted on the neighborhood's roads to be stomped on by marchers in a show of defiance.