BAGHDAD, Iraq — The massive car bombs that killed nearly 100 people and wounded more than 500 in Baghdad on Wednesday morning offered powerful new evidence of the enduring strength of Sunni extremists nearly two months after U.S. troops all but disappeared from Iraqi cities.

The early morning blasts, by far the deadliest since the June 30 withdrawal of U.S. troops from cities, raise fresh questions about whether American troops disengaged from Baghdad too quickly and whether the recent violence will lead them to try to assert more control over security, at the risk of embarrassing and unsettling Iraq's government.

The coordinated attacks targeted prominent ministries, marking the most crippling attack on the Shiite-led government to date. Despite a recent U.S. focus on tension between Arabs and Kurds in northern Iraq, Wednesday's strikes suggested that the sectarian fight between Shiites and Sunnis over dominance of Iraq remains far from over.

U.S. military officials in Baghdad said there is little they can do in response to the surge in violence other than pressure Iraqi Prime Minister Nouri al-Maliki to be more cautious as the Iraqi government take control of the country's security. Senior American officials have criticized Maliki for recent decisions that they consider overconfident and impulsive. Since the June 30 urban drawdown, his government has sharply restrained the mobility and authority of U.S. troops and his security forces have begun removing blast walls along major roads, declaring the capital safe.

Retired Col. Peter Mansoor, a senior advisor to the top American commander in Iraq in 2007 and 2008, said the Iraqi government is unlikely to ask the U.S. military to resume its presence in Baghdad.

"Regrettably, I think we can't go back in," he said, saying that such a move would in any event be unpalatable to most Americans and Iraqis. "The Iraqi government got ahead of itself. It is declaring the war over when it is far from over."

His comments echoed those of other U.S. military officials, who say the U.S. has reached a point of diminishing returns in its ability to influence Iraqi decisions.

The bombs, which exploded outside the Foreign and Finance ministries in heavily guarded areas of downtown Baghdad, detonated in close succession shortly after 10:30 a.m.

The deadliest blast left an enormous crater a few feet from the Foreign Ministry, which is near the Green Zone. At least 60 people were killed, mostly ministry employees, and 315 were wounded, Iraqi authorities said.

The blast targeting the Finance Ministry killed at least 35 people and wounded 228, Iraqi officials said. The explosion caused an overpass to collapse and left the building, which had only recently been repaired after a bombing in 2007, in shambles.

Maliki blamed the attacks on former officials of Saddam Hussein's regime and vowed to revamp security measures.

In recent months, as violence has increased in northern Iraq, in part fueled by tension between Arabs and Kurds, U.S. officials have said the that fault line has surpassed the Sunni-Shiite schism as the biggest threat to the country's stability. Wednesday's carnage led some to suggest that call was premature. U.S. officials have been urging Maliki in recent months to take more meaningful steps to reconcile with Sunnis, even those with links to Saddam Hussein's regime, to little avail.

"The Maliki government doesn't seem to be holding to its deals," said Stephen Biddle, a senior fellow at the Council on Foreign Relations, who frequently advises U.S. officials on Iraq and Afghanistan policy. "The Sunnis seem to be saying that there are costs to the government's actions."

He said American officials must use their diminishing influence in Iraq to foster reconciliation.

"We no longer have coercive leverage," Biddle said. "Now the challenge is to persuade ... Part of what needs to change is Maliki's behavior."

Retired Lt. Col. Doug Ollivant, a planner in Baghdad in 2007 who recently served as an Iraq expert on the National Security Council, said the recent attacks do not appear likely to plunge the country back to the point of staggering violence and near-anarchy reached in 2007.

"At the strategic level, the bombings don't appear to be having the effect al-Qaida wants," he said. "It's not rekindling a civil war."

Still, the ravaged buildings, thick plumes of smoke and incessantly wailing sirens brought back the sights and sounds of the darkest days of the war.

Ibrahim Mohammed Ibrahim, 58, an official at the Foreign Ministry, had just sent off his 24-year-old son, also a ministry employee, to the mailroom when the blast shook the building, shattering all its windows and sending large chunks crushing to the ground.

"I ran upstairs trying to find him and could hardly reach him because of the dead bodies lying on the floor," he said Wednesday night. "When I found my son, he was drenched in blood." A piece of glass had pierced Gassan's heart, killing him.

Hours later, after the dead and wounded had been taken away, the scene outside the ministry was apocalyptic. Scores of cars were mangled beyond recognition. Trees were stripped of leaves and branches. The stench of burned rubber lingered in the air.

Gazim Mohammed, 54, sat outside, under the scorching sun, looking dejected as he watched the building. Two of his sons work at the ministry and they were not answering their phones.

"They've disappeared," he said quietly.

Teams of American explosives disposal experts and army trainers responded to Wednesday's bombings, and American Apache helicopters hovered overhead. Some U.S. soldiers stood on the roof of the building across the street from the Foreign Ministry while others established a security cordon. Soldiers took photographs and searched through debris outside the foreign ministry.

"Just make sure you photograph us doing nothing," one of the American soldiers said wryly to a reporter taking photos. "Because that's what we're supposed to be doing now."

A few miles across town, at al-Kindi Hospital, Mohammed Nouri, 45, shuffled from one room to another to tend to his two brothers, who were gravely wounded in the Finance Ministry bombing.

"The civilians are the ones getting killed," he said, taking a break from cleaning the blood off his bare-chested brother, Salah, 36, as he complained faintly about his sore head. "The government needs to protect them."

Next door, doctors used scissors to remove blistered, burned flesh from the feet of his younger brother, Abas.

Abas and Salah were driving by the Finance Ministry when the overpass they were on collapsed, sending their pick-up truck crashing down, where it caught fire.

"Now I've become jobless because my car is burned," said Salah, a truck driver whose face, arms and chest were also burned. "That's the only way I have to make a living. My car is destroyed and I am sure the government will never help me."

The patient in front of him, a senior official at the Finance Ministry, said he has little faith in the government's ability to defeat the insurgency. The 53-year old official, who declined to give his name, said American troops withdrew from Baghdad too soon.

"There is infiltration everywhere in the state, especially in the security forces," he said. "Today the entire city was targeted. How do you justify that?"

Jaffe reported from Washington. Special correspondents Qais Mizher and Zaid Sabah contributed to this report.