Outside the Iraqi parliament, a tan-colored crane lifts slabs of concrete. Soldiers maneuver them into place, adding a second layer of blast walls near the entrance to what is already one of the most fortified buildings in the Iraqi capital.
Around Baghdad's Green Zone, once the heart of the US occupation and now the fortified seat of government, some of the concrete walls are going back up. They were pulled down a year ago in what the Iraqi government called an acknowledgment of improved security.
Ten years after the US-led invasion that toppled Saddam Hussein, talk swirls in government circles of Sunni protesters planning to destabilize the country. Unlike previous threats from Al Qaeda in Iraq, they say this one would come in the guise of demonstrators.
"If the government let them they would reach the borders of the Green Zone and then within seconds Al Qaeda and the Baath party would enter ... and a massacre would take place," says Kamal al-Saidi, a member of Prime Minister Nouri al-Maliki's Shiite State of Law coalition in parliament.
While many discount the possibility of a coup, rising sectarian tension and an ongoing political crisis have raised fears that there is a new battle looming between Baghdad and the provinces.
Protests began in December following the arrest of bodyguards of a Sunni cabinet minister from the Iraqiya political bloc. They are now a weekly phenomenon with tens of thousands of demonstrators turning out after Friday prayers in cities with Sunni majorities.
At a recent Friday protest, clerics demanded that Sunni rights be restored and Iranian influence rolled back. One cleric called for Turkey to step in and resume its Ottoman-era role of protecting a Sunni region. At another protest, a group of young men sang that they were followers of Al Qaeda.
Although the demonstrations have been largely peaceful, some officials fear that their political leaders have lost control.
"Now there is a new generation of Sunni leaders, tribal religious leaders who have taken it over. So with whom do you talk to who represents these people?" says a senior Iraqi official who asked not to be identified.
In the office of a Sunni party, aides waiting for their leaders to reach a budget agreement said they feel the Maliki government is ignoring the substance of their demands.
"We're being marginalized," said one young man who did not want to give his name. "We're not against the government, but the government could take action on this issue."
Protesters in Sunni areas have demanded the release of several thousand prisoners held under antiterrorism laws, reinstatement of former Army officers, and the hiring of more Sunnis in the Shiite-dominated security forces.
Followers of Shiite cleric Moqtada al-Sadr recently held demonstrations demanding prisoner releases – but rather than protests in solidarity with Sunni areas, they demanded that Palestinians in Israeli jails be freed. Shiite parties themselves have also fragmented, with Sadrists pulling away from supporting Mr. Maliki.
"These multiple identities competing with each other is what fuels the crisis you see in Iraq's political landscape," says an Arab analyst with long experience in Iraq who asked not to be named. "In 2003 when the genie of ethno-sectarianism came out of the bottle it gave rise even to subsectarian divisions.... Communities live in fear of each other."
In Karrada, traditionally a largely Christian neighborhood, a new poster of Iranian Grand Ayatollah Khomeini with Mr. Sadr's father looks down on a roundabout, praising "the revolution and martyrdom."
Those looking for signs of Iranian encroachment point to the billboard as proof.
But Hussein Majid, selling soft drinks to passing cars just below it, isn't bothered.
"I'm Sunni, but I don't worry about it," he says. "I don't follow the news, and I don't pay attention to politics."
He has been at the same spot for 10 years – since he was 12.
Ali Fajil, another vendor, watched Iraq degenerate into civil war seven years ago. Now? "I am 100 percent convinced sectarianism won't be back."