LONDON — A senior commander launched an 8,000-troop offensive against Al Qaeda in southern Baghdad yesterday with a warning that operations to quash Iraq’s insurgents need to be sustained at today’s levels until next spring. American forces under the command of Major General Rick Lynch and backed by Iraqi allies carried out pre-dawn airborne raids on insurgent strongholds south of the capital at the start of operation “Marne Avalanche.” The objective is to disrupt the flow of terrorists and vehicle-borne bombs into Baghdad. “Marne Avalanche” is the latest in a succession of campaigns on the capital’s periphery, designed to ensure the “surge” of 28,000 additional American forces in central Iraq is not derailed by violence. General Lynch made clear that commanders on the ground reject the chorus coming from those calling for withdrawal from Iraq. The up-and-coming commander has been in charge of a key battleground, one of a handful where the surge will be won or lost, since March. He said he had identified four terrorist safe havens in his command area. “It’s going to take us through the summer and fall to deny the enemy his sanctuaries,” he said. “And then it’s going to take us through the first of the year and into the spring.”

He said he had given local residents his word that the American military would restore order before handing over to an Iraqi force capable of defending the civilian population. “What they’re worried about is our leaving,” he said. “And our answer is: ‘We’re staying,’ because my order from the corps commander is that we don’t leave the battle space until we can hand over to the Iraqi security forces.”

America’s second-ranking officer in Iraq, Lieutenant General Raymond Odierno, appealed yesterday for the military to be granted the time to pacify the country. “My assessment right now is, I need more time,” he said. “I’m seeing some progress now here in Iraq. We have really just started what the Iraqis term ‘liberating’ them from Al Qaeda. What I’ve got to determine is what do I need in order to continue that progress so that the political piece can then take hold and Iraqi security forces can hold this for the long term.” In northern Iraq at least 85 people were killed by a suicide truck bomb in the divided city of Kirkuk. Another 180 people were injured in the blast, which trapped dozens of people on a burning bus. Kirkuk has seen tensions across its four-sided ethnic divide ahead of a referendum on its future provincial status.