Traffic clogged the capital's main thoroughfares for the first time in several days, after a vehicle ban imposed by Prime Minister Nouri al-Maliki in the wake of Wednesday's suspected Al Qaeda bombing of the minarets at the Askariya shrine in Samarra, north of the capital.

Lines of vehicles snaked around the block where gas stations had been shut for days, and vendors spread fresh vegetables across wooden stands in bustling wholesale markets. Packed buses motored slowly over bridges spanning the Tigris River.

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The curfew was lifted just hours after a top American general acknowledged that security forces have full control in only 40 percent of the city.

Lt. Gen. Raymond Odierno's assessment came as a U.S.-Iraqi effort to pacify Baghdad entered its fifth month, with 30,000 additional U.S. troops now in place. But the city has so far seen little improvement in overall violence, and a tense political standoff was under way between the U.S.-backed government and Shiite lawmakers who suspended their participation in parliament.

Odierno said American troops launched a new offensive Friday night in Baghdad's Arab Jabour neighborhood and in Salman Pak, a town just southeast of the capital. It was the first time in three years that U.S. soldiers entered those areas, where Al Qaeda militants build car bombs and launch Katyusha rockets at American bases and Shiite Muslim neighborhoods.

The overall U.S. commander in Iraq, Gen. David Petraeus, said during a news conference Saturday with visiting Defense Secretary Robert Gates that the operation would put troops into key Al Qaeda-held areas surrounding Baghdad.

Odierno said there was a long way to go in retaking the city from Shiite Muslim militias, Sunni Arab insurgents and Al Qaeda terrorists. He said only about "40 percent is really very safe on a routine basis" -- with about 30 percent lacking control and a further 30 percent suffering "a high level of violence."

The U.S. ground forces commander discussed the new offensive and the security situation in an interview with two reporters as he visited an American outpost near the main market in the capital's southern Dora district, a major Sunni Arab stronghold.

"There's about 30 percent of the city that needs work, like here in Dora and the surrounding areas," Odierno said. "Those are the areas that we consider to be the hot spots, which usually have a Sunni-Shiite fault line, and also areas where Al Qaeda has decided to make a stand."

The U.S. military released a statement Sunday saying its forces killed ten suspects and captured 20 in weekend raids across Iraq.

Another statement said U.S. attack helicopters had killed four suspects and wounded three in operations south of Baghdad. The aircraft were operating in support of Iraqi army soldiers on the ground, who were engaged by insurgents, it said. The incident took place Friday.

Suspected militants fired on the helicopters as they swooped in, then ran into a nearby structure, the statement said. One of the helicopters fired on the building, destroying it.

Afterward, Iraqi soldiers found three sniper rifles, multiple hand grenades and black masks scattered amid the ruins of the building, the military said.

Elsewhere, a car bomb killed two Kurdish security agents Sunday morning in Iraq's oil-rich northern city of Kirkuk, police said.

The men were traveling in a civilian car through downtown Kirkuk when a parked car bomb exploded next to their vehicle, said police Brig. Sarhat Qadir. Three pedestrians were injured, he said.

Kirkuk, an ethnically mixed city, lies 180 miles north of Baghdad.

South of the capital, a roadside bomb went off next to an Iraqi police patrol in Nasiriyah, wounding two policemen, authorities said. Nasiriyah is predominantly Shiite city about 200 miles southeast of Baghdad.

Complete coverage is available in FOXNews.com's Iraq Center.