BAGHDAD, 29 March 2008 — US forces were drawn deeper into Iraq’s four-day-old crackdown on Shiite militia gunmen yesterday, launching airstrikes in Basra for the first time and battling fighters in Baghdad, while Britain ruled out deploying any troops to Basra yesterday, despite days of intense battles on the streets and signs Iraq’s forces cannot cope with a growing uprising.

“This is an Iraqi-led operation and it’s one that we have wanted to see since they took responsibility for security in Basra,” said a spokesman for Britain’s Ministry of Defense. “It’s going to take time, but it shows the Iraqi government’s political will in taking on the militants.”

The fighting has exposed a rift within the majority Shiite community and put pressure on Prime Minister Nuri Al-Maliki, whose forces have failed to drive fighters loyal to cleric Moqtada Sadr off the streets of Iraq’s second-largest city.

Authorities shut down Baghdad with a strict curfew, but that did not halt rocket attacks and clashes in the capital. Defense Minister Abdel Qader Jassim acknowledged that Iraqi security forces had been caught off-guard by their foes.

“We supposed that this operation would be a normal operation, but we were surprised by this resistance and have been obliged to change our plans and our tactics,” he told a news conference in Basra. Reporters were brought to the briefing in military vehicles and kept inside because of clashes nearby. Parliament called an emergency meeting to end the impasse, but just 54 members of the 275-seat body managed to get inside the fortified “Green Zone” government and diplomatic compound, which was bombarded by rockets as they gathered.

One missile hit the Green Zone office of Vice President Tareq Al-Hashemi, killing a security guard. The US Embassy ordered its staff in the zone to stay under cover when possible and wear body armor and helmets when in the open.

Al-Maliki, who had given the Basra militants 72 hours to surrender, extended his deadline, giving them until April 8 to turn in their weapons for cash.

But Sadr’s Mehdi Army fighters remained defiant. “We will fight on and never give up our weapons,” Mehdi Army deputy military commander in Basra Abu Hassan Al-Daraji told Reuters by telephone. “We will not turn over a single bullet.”

The government says it is fighting “outlaws,” but Sadr’s followers say political parties in Maliki’s Shiite-led government are using military force to marginalize their rivals ahead of local elections due by October.

The Iraqi ground commander in Basra, Maj. Gen. Ali Zaidan, said his forces had killed 120 “enemy” fighters and wounded around 450 since the campaign began on Tuesday. But Reuters television footage from Basra showed masked gunmen from Sadr’s Mehdi Army still in control of the streets, openly carrying rocket launchers and machine guns.

A British Ministry of Defense spokesman said US warplanes had opened fire in Basra for the first time, dropping bombs in support of Iraqi units on the direction of US or British control teams operating with Iraqis on the ground.

The fighting has trapped Basra residents in their homes, raising fears of a humanitarian crisis. The United Nations said it was standing by with blood bags, trauma kits, 200 tons of emergency food and 39 million water purification tablets.

Sadr, who helped install Al-Maliki in power after an election in 2005 but later broke with him, has called for talks. But Al-Maliki has vowed to battle on with no negotiations.

The clashes have all but wrecked a truce Sadr declared last year, which Washington had said helped curb violence. A witness said Mehdi Army gunmen had seized control of the southern city of Nassiriya. Mehdi Army fighters have also held territory or fought with authorities in Kut, Hilla, Amara, Kerbala, Diwaniya and other towns throughout the Shiite south over the past several days.

In Baghdad there have been clashes in at least 13 mainly Shiite neighborhoods, especially Sadr City. “There have been engagements going on in and around Sadr City. We’ve engaged the enemy with artillery, we’ve engaged the enemy with aircraft, we’ve engaged the enemy with direct fire,” said Maj. Mark Cheadle, a spokesman for US forces in Baghdad.