U.S. Defense Secretary Robert Gates is in Iraq for a previously unannounced visit, one day after bombs killed nearly 200 people in Baghdad's worst violence in months.
Gates arrived in Iraq from Israel, saying he would tell Iraqi leaders the U.S. military commitment to their country is not open-ended.
He called Wednesday's bombings "horrifying," but said the attacks would have no effect on U.S.-led efforts to improve security in Baghdad.
Gates has used his Middle East tour to call on the states in the area to help stabilize Iraq, saying chaos there would hurt the entire region.
Iraqi Prime Minister Nouri al-Maliki also condemned Wednesday's attacks on mostly Shi'ite areas of Baghdad, calling those responsible "soldiers of Satan."
Meanwhile, a suicide car bomber struck a Shi'ite district in Baghdad Thursday, killing 11 people.
Mr. Maliki ordered the arrest of an Iraqi army colonel in charge of security of the Sadriyah market area, which was the site of Wednesday's deadliest attack.
U.S. military officials say they suspect the bombings were the work of al-Qaida in Iraq terrorists and their Sunni insurgent allies trying to inflame sectarian passion.
In Israel, Gates and Israeli Prime Minister Ehud Olmert discussed Iran's nuclear program. Gates said the U.S. favors diplomatic efforts to resolve the situation.
Some information for this report was provided by AFP, AP and Reuters.
