A series of coordinated attacks Monday in Iraq left more than 100 people dead and hundreds of others injured. Authorities in Baghdad said insurgents detonated car bombs, stormed military bases and attacked checkpoints in the bloodiest attacks of the year.
Victoria Nuland, a spokeswoman for the U.S. State Department, said the attacks were the work of al-Qaida in Iraq, an organization making "desperate efforts" to incite sectarian unrest in the country.
A string of al-Qaida attacks in Iraq four years after U.S. forces invaded in 2003 sparked sectarian conflict that pushed the country to the brink of civil war. Infighting between political leaders from the Shiite, Sunni and Kurdish communities, meanwhile, are hampering overall development.
Nuland said Washington was "concerned" about the string of attacks in Iraq and was ready to provide any support that Baghdad might request.
"They fought long and hard to get to this stage where they are taking responsibility for their own security," she said. "But as necessary, we provide support."
U.S. military forces withdrew from Iraq in December.