BAGHDAD — A barrage of rockets hit Baghdad's fortified Green Zone on Saturday, casting doubt on the influence of a Shiite militia cease-fire less than 24 hours after it was renewed.
At least six blasts resonated across the U.S.-protected enclave, which is home to Iraqi government offices, the U.S. Embassy and military bases. An American official said there were no casualties and no reports of significant damage.
Along Iraq's frigid northern border, Turkish forces pressed their largest ground offensive in years against Kurdish separatist guerrillas, pounding rebel targets with artillery and helicopter gunfire.
The Turkish military command said that as many as 79 rebels had been killed along with seven of its troops since the incursion began Thursday night.
Ahmed Denis, a rebel spokesman, declined to confirm the number of Kurdish casualties, but said rebels had recovered the bodies of 15 Turkish soldiers. He also said rebels shot down a Turkish helicopter Saturday.
Neither side's account could be independently verified.
The Green Zone attack was the week's fourth rocket barrage in the capital, where U.S. commanders have touted a decline in violence of more than 60% since June.
Navy Rear Adm. Gregory Smith, a military spokesman, blamed the previous attacks on breakaway factions of radical Shiite cleric Muqtada Sadr's powerful Mahdi Army militia, groups that U.S. commanders allege receive support and direction from Iran. There was no immediate comment on who may have been behind the latest Green Zone attack.
The other targets last week included Baghdad's international airport and the U.S. military's adjoining Camp Victory complex. Five Iraqis and a U.S. civilian were killed in those attacks, which also injured three U.S. soldiers and more than 14 Iraqis.
The attacks took place despite the six-month truce Sadr declared in August and renewed Friday in a much-anticipated announcement read in mosques during midday prayers. They raised questions about the anti-U.S. cleric's ability to rein in splinter groups, which have ignored his order to stand down.
Joost Hiltermann, Middle East director for the International Crisis Group, said the latest rocket attack could be "an Iranian signal that the Americans shouldn't over-exult in the Sadrist cease-fire: There won't be an easy ride."
Iran denies U.S. accusations that it provides weapons, training and funds to Shiite militiamen in Iraq.
Many in Sadr's movement are disgruntled about the truce, which they complain has been used by the U.S. military and Shiite rivals within the Iraqi security forces to target his followers.
American authorities promised Friday to treat those who honor the cease-fire with "respect and restraint." But the military said in a statement that it would continue to pursue "these criminals who violate the law and dishonor the commitment made by al-Sayid Muqtada."
The statement used a title for Sadr that denotes descent from the prophet Muhammad. The tone was in stark contrast to statements just over a year ago, when the U.S. military identified Sadr's militia as the single greatest threat to security in Iraq.
Mahdi militiamen helped drive the sectarian killing that once left dozens of bodies in the streets of Baghdad every day; three bodies were found Saturday.
U.S. officials say Sadr's cease-fire played a key part in the ebb in violence since the U.S. completed a buildup of 28,500 additional troops, most of whom are due to leave this year. They also credit a rebellion by tens of thousands of Sunni Arab tribesmen against the Islamic extremists they once backed.
Sadr ordered his militia to lay down its arms last summer after clashes with a rival Shiite group killed at least 52 people in the holy city of Karbala. He said at the time that he wanted to use the truce to instill discipline in the ranks.
On the Turkish front, Iraqi Prime Minister Nouri Maliki received a telephone call from his Turkish counterpart, Recep Tayyip Erdogan. The Iraqi leader warned Erdogan to avoid actions that could threaten stability in the semiautonomous Kurdish region or hurt civilians, Maliki's spokesman, Ali Dabbagh, told reporters.
Turkish officials have said they are targeting only hide-outs of the Kurdistan Workers Party, or PKK, which uses the border region to launch attacks on their forces.
There have been conflicting accounts of the scale of the offensive.
Turkish news media reports say about 10,000 troops have pushed more than 10 miles into Iraq in pursuit of the militants, but Iraqi and rebel officials say the invading force is much smaller.
Kurdish authorities Saturday pulled back members of the regional peshmerga security force to avoid a clash with the Turkish troops, but vowed to respond forcefully to any attacks on Kurdish civilians in northern Iraq.
The United States, which has confirmed that it received advance notice of the Turkish operation, has urged restraint. Washington considers the PKK a terrorist organization and has said that Turkey has the right to defend itself.
In other developments Saturday, at least four people drowned when a boat carrying Shiite pilgrims to Karbala for a religious holiday capsized in the Tigris River north of Kut, 100 miles southeast of Baghdad, police said. Rescuers continued searching for two missing people.
More than 4 million pilgrims have so far converged on Karbala for this week's Arbaeen rites, which mark the 40th day of mourning following the anniversary of the death of Imam Hussein, a grandson of the prophet Muhammad and one of Shiite Islam's most revered figures.
In Baghdad, Shihab Timimi, the head of Iraq's main journalists union, and his son were wounded when gunmen opened fire on their car, colleagues said.
Times special correspondents Asso Ahmed in Sulaymaniya, Yesim Comert in Istanbul, Turkey, and Saad Fakhrildeen in Najaf contributed to this report, along with correspondents in Baghdad.