The attacks are supposed to be planed and executed by al-Qaeda related groups. Another fatal attack has as victims two soldiers, killed by a roadside bomb in the north of Baghdad. The attacks occurred despite the fact that the security forces in Iraq have been taking major measures of security and increased the checkpoints on the pilgrim routes.
Arbaeen is one of the largest pilgrimage on Earth, involving over 15 million people. The city of Karbala, in Iraq, is the third holly place of Shia Islam. Observance of Arbaeen in Karbala was banned for many years when Saddam Hussein was president of Iraq. Arbaeen reached over 18 million participans in 2013.