More than 80 people have been killed, and almost 300 wounded, by a wave of bombing across Iraq, including 10 neighborhoods in Baghdad, that suggests sectarian violence in the country simply will not abate six months after the departure of U.S. troops.

Most of the dead were Shia Muslim pilgrims who were assembling for a religious festival and observing the anniversary of the death of Moussa al-Kadhim, an 8th-century Shia imam.

While no group has taken responsibility for the killings, it is widely suspected that Sunni militants with ties to al-Qaida are behind the atrocities -- in yet another attempt to destabilized Iraq and upend the government of Shia Prime Minister Nouri Maliki.