In recent weeks, the security forces have undertaken a series of operations, mostly in Sunni neighborhoods, as part of a campaign the government is calling “the revenge of the martyrs.” The Shiite-dominated government claims to have arrested hundreds of Sunni extremists and discovered a factory that makes car bombs, but the operations have further antagonized the Sunni community, with only limited effect on reining in the violence.

The government has also engaged in a public relations campaign by releasing statements in the wake of the attacks that state lower death tolls than those reported by other security officials. Around midday on Wednesday, the Ministry of Interior published a statement online reporting that 18 people had been killed. However, a government official who for years has provided casualty figures to the news media had already said that more than 60 people had been killed.

The surge in violence in Iraq is partially the result of spillover from the civil war in Syria, where Qaeda-linked groups fostered by Iraqi extremists are some of the fiercest fighting units. The groups’ successes in Syria have emboldened Sunni extremists in Iraq to step up their fight. The war has also exacerbated sectarian tensions within Iraq as the country’s Shiites, who make up the majority of the population, have largely sided with the Syrian government, while Sunnis are backing the Syrian rebels, fellow Sunnis.

Opponents of the government, who since the Arab uprisings unfolded in 2011 have sought to organize a protest movement in Iraq, had been planning demonstrations for Saturday. However, on Wednesday the government directed citizens not to gather in protest because of the risk of further violence.

For Iraqis, the car bomb attacks are terrifying enough. But in recent days, grisly images of executions by Al Qaeda’s Iraq affiliate, a Sunni insurgent group that has renamed itself the Islamic State in Iraq and Syria to reflect its growing role in both countries, have emerged on the Internet.