President Barack Obama spoke by phone Saturday with Iraqi Prime Minister Haider al-Abadi, with both leaders agreeing on what the White House said was the "critical importance" of improving security in Baghdad's fortified International Zone.
A White House statement said Obama also extended condolences on behalf of the American people for the recent terrorist attacks in Baghdad.
The talks, which the statement said also stressed the importance of continued dialogue among Iraq's political parties, came less than a day after protesters defied bullets and tear gas to storm the zone, which houses parliament and an array of government installations.
The anti-government protesters, who were later driven from the area, vowed to return with weapons.
Many of the protesters were followers of Shi’ite cleric Muqtada al-Sadr, who, like many other political leaders in Iraq, has his own militia, known as the Peace Brigades.
Sadr came out in support of what he described as the people’s “revolution” against the government.
Iraqi riot police prevent protesters from storming the provincial council building during a demonstration in Basra, 340 miles (550 kilometers) southeast of Baghdad, Iraq, early Saturday, May 21, 2016.
Security forces Saturday blocked all the entrances to the International Zone and increased the number of special forces checkpoints on city streets.
Inside the zone, some 40 Humvees were parked outside the parliament, and security forces were posted at key points.
Some Baghdad residents stocked up on food, water and medicine out of fear that the situation could get worse and protesters could start rioting and looting in the city.
One resident of Sadr City, a densely populated and impoverished pro-Sadr area of Baghdad, said the country did not need two wars.
“We already have a war against Islamic State, and this is more important,” said Ali, speaking on condition his last name not be used. "If we start a war against the government, we will have two wars, and this is not good for us. First, we should resolve the fight against IS.”
Ali warned that the bigger danger was an armed conflict between different Shi’ite militias: those loyal to al-Sadr, and the powerful pro-Iranian militias of the Badr Organization and the Islamic Supreme Council of Iraq.
Iraqi riot police spray water and tear gas to prevent protesters from storming the provincial council building during a demonstration in Basra, 550 kilometers (340 miles) southeast of Baghdad, Iraq, May 21, 2016.
The pro-Iranian factions that are loyal to key Shi’ite government leaders have sent veiled warnings for al-Sadr to stand down.
But al-Sadr has emerged as one of Iraq’s most powerful nationalist and populist leaders, and he has proved he can mobilize hundreds of thousands of Iraqis who are fed up with government corruption and the leadership's inability to protect them from repeated rounds of violence.
Friday’s protest followed a series of bombings in Baghdad that left more than 100 dead and hundreds wounded, mostly Shi’ites from the city’s poorer neighborhoods.
Iraqi riot police prevent protesters from storming the provincial council building during a demonstration in Basra, 550 kilometers (340 miles) southeast of Baghdad, Iraq, May 21, 2016.
Al-Sadr's re-emergence came as analysts increasingly describe Abadi’s leadership as weak. His previous denunciation of protesters who forced their way into the International Zone three weeks ago to take over parliament was clearly ignored.
The prime minister’s attempts to ease tensions by restructuring the government also have failed, and he has been unable to pull together the different political factions squabbling for power.
The U.N. special envoy to Iraq called for a de-escalation of the situation.
“Restoring calm is key for Iraq to be able to move forward in finding a political solution,” Jan Kubis said in a statement released Saturday.