The attack, which struck a tent in which soldiers and contractors were eating, killed at least 15 U.S. soldiers and two Iraqi soldiers. Several contractors were also reported killed. Officials say 66 people -- among them 42 U.S. soldiers were wounded.
A U.S. military spokesman says it is still unclear whether the blast was caused by a rocket fired into the tent or by a bomb. But the Al-Qaeda-linked Army of Ansar Al-Sunnah group has claimed credit, saying a suicide bomber was responsible.
In Washington, President George W. Bush offered condolences but said he remains confident democracy will prevail in Iraq.
"I know a free Iraq will lead to a more peaceful world," Bush said. "So, we ask for God's blessings on all who are involved in that vital mission."
In other developments, French Foreign Minister Michel Barnier flew to Baghdad today to pick up two French journalists who were released after four months in captivity. They are scheduled to return to France late today.
Polish Prime Minister Marek Belka, paid an unexpected visit to Iraq today to meet with the Polish contingent of 1,700 troops.
(dpa/AP/Reuters/AFP)For more on events in Iraq, see RFE/RL's dedicated The New Iraq webpage.