Baghdad, Iraq ? Government forces fanned out across Baghdad on Wednesday, setting up checkpoints, frisking motorists and causing huge traffic jams on the first day of the largest security operation in Iraq’s capital since Saddam Hussein’s ouster three years ago.

President Bush, back in Washington after a surprise visit to Iraq, said the crackdown offered the promise of reducing the violence that has plagued the capital.

The only reported clash between army troops and gunmen in Baghdad occurred just before noon in the Azamiyah neighborhood, when heavy exchanges of gunfire shattered the late morning quiet and sent residents, including women and children, scurrying for cover.

Overall, violence dipped slightly in the capital Wednesday, with just one car bombing killing four and wounding six. Another four people died in separate shooting incidents around Iraq.

Many stores were shut in Azamiyah and Dora, both strongholds of the Sunni Arab insurgency. Entire streets looked virtually deserted in Dora, including one residents have dubbed “death road” because of the frequent clashes there between insurgents and police.

“If this security plan really works, then perhaps I will be encouraged to go out of my neighborhood,” Mohammed Yehia, a 30-year-old father of two, said at the marble-tiled plaza outside the Grand Imam Abu Hanifa mosque in Azamiyah.

Iraqi Interior Ministry commandos stop cars at a checkpoint in the Dora neighborhood of Baghdad, Iraq. Iraqi troops were out in force and cars were backed up at checkpoints Wednesday in Baghdad as Prime Minister Nouri al-Maliki launched a major security crackdown aimed at ending the violence that has devastated the capital.

Yehia said fears of being killed by Shiite militants have prevented him from venturing out of Azamiyah since the Feb. 22 destruction of a revered Shiite shrine – an attack that unleashed the worst and longest bout of sectarian violence since Saddam’s ouster.

“It has been three years,” said Yehia, who makes a living doing odd jobs at the Grand Imam mosque. “We have had enough. We are all yearning for normal lives.”

Operation Forward Together, involving 75,000 Iraqi army and police forces backed by U.S. troops, began at a crucial time – one day after Bush visited Baghdad to reassure Iraqis of Washington’s continued support and exactly a week after the death of terror leader Abu Musab al-Zarqawi.

It was also the first major action by Prime Minister Nouri al-Maliki since his new government of national unity was sworn in on May 20, and a week after he gained the consensus he needed from Iraq’s ethnic and sectarian groups to fill three key posts – defense, interior and national security.

Tackling Baghdad’s tenuous security has been the aim of several past counterinsurgency operations – including one a year ago. That operation, code-named Lightning, failed to have any impact on the bombings, shootings and killings that have become daily fare in Baghdad.

Al-Maliki pledged Wednesday not to negotiate with those who had shed innocent blood, the latest in a series of tough statements he has made since American bombs killed al-Zarqawi, the leader of al-Qaida in Iraq.

But it remains to be seen whether al-Maliki, a veteran politician with years of experience as an opposition activist in exile, can back up his uncompromising rhetoric with action.

What he can do is count on Bush and the 132,000 American troops in Iraq.

In a Rose Garden news conference barely more than six hours after his return from Baghdad, a buoyant Bush insisted that U.S. troops would stay until Iraqi forces can do the job on their own.

“If we stand down too soon, it won’t enable us to achieve our objectives,” the president said. He said those goals include an Iraq that can govern, sustain and defend itself.

Unlike al-Maliki, not everyone in Baghdad was welcoming of Bush.

About 2,000 followers of radical Shiite cleric Muqtada al-Sadr, whose militiamen fought U.S. troops in 2004, staged a noisy demonstration to protest Bush’s visit.

“Iraq is for Iraqis” and “No to the occupation,” they chanted.