It appears that the Islamic State is in the midst of a spring offensive. One of its main tactics has been to use more car bombs in terrorist attacks.
In May there have been two major days of vehicle bombs. The first was on May 1 when two car bombs went off in Muthanna’s Samawa killing 38 and wounding 86. Afterward three IS members were arrested and admitted to carrying out the operation. According to Al Mada they had a scout check out the locations for the bombing in Samawa. Once one was found a day and time for the bombing was picked. Suicide bombers and four car bombs were then moved from Anbar, through Nukhaib in Karbala to Muthanna. A guide took them through back roads skipping all of the security checkpoints. Two of those bombs detonated, one was discovered by the security forces and dismantled, while the fate of the fourth was unknown. Ten days later on May 11 three suicide car bombs went off in Baghdad’s Sadr City, Kadhimiya and Jamiya leaving a total of 103 dead and 170 injured. Al Maalomah quoted an Iraqi security analyst who claimed that the Sadr City bombing originated in Diyala. He told the paper that the parts were smuggled through checkpoints into the capital, and then assembled for the attack.
Both of these operations highlight the Islamic State’s networks. The group has rat lines stretching from Anbar, Salahaddin, Diyala, and Babil into the capital, which it has operated for years. Payoffs and threats allow it access through checkpoints, plus there are rural roads that it uses to that avoid the security forces to enter the urban areas. The government has always split security in Baghdad between a variety of commands and units and security forces to prevent coups. That means that it is impossible to ensure the safety of the province. As for the south, Babil used to be its main base for operations there. The Muthanna bombing showed that it can now move men and material from Anbar throughout the region. The south has not been hit for months, but it now appears vulnerable.
BBC, "IS conflict: Dozens killed in Baghdad car bombings," 5/11/16
Al Mada, “Details on Samawa Attacks: 4 who infiltrated from the swamp and delivered two suicide bombers from Anbar,” 5/9/16
Al Maalomah, “How the car bomb entered Sadr City?” 5/11/16
Salaheddin, Sinan and George, Susannah, "Additional Bombings Bring Death Toll to 93 Across Baghdad," Associated Press, 5/11/16
Sotaliraq, "Statistics: Killing 103 people and injuring 155 in Baghdad bombings on Wednesday," 5/11/16
Sputnik News, "Death Toll in Southern Iraq's Twin Blasts Rises to 38," 5/1/16