BAGHDAD, Iraq - The U.S. military displayed images of the battered face of Iraq's most feared terrorist Thursday and Iraqis celebrated with gunfire after American bombs killed the leader of al-Qaida in Iraq. It was a long-sought victory for U.S. forces, but officials cautioned of violence ahead - and a string of blasts proved that prediction almost immediately.

Within minutes of the announcement of Abu Musab al-Zarqawi's death, Prime Minister Nouri al-Maliki named three key security ministers - military and political breakthroughs in rapid succession that marked the biggest potential turnaround in Iraq in months.

The two events may give the United States and its Iraqi allies another brief chance to build momentum toward stability and away from violence. With al-Zarqawi out of the way and the new government in place, some Sunni Arab leaders may be emboldened to resume a dialogue they started last fall - exchanges sunk by al-Zarqawi's al-Qaida in Iraq.

If another effort is made, much will depend on the Iraqi government's ability to live up to its promises to build a political system that includes all groups, including disaffected Sunnis. More than a dozen Sunni Arab insurgent groups are believed to be operating in Iraq, and a few use tactics just as ruthless as al-Zarqawi's.

“This popular front and national unity is our guarantee to fighting all challenges,” al-Maliki told a Baghdad news conference. But, he warned, “whenever there is a new al-Zarqawi, we will kill him.”

President Bush and U.S. military leaders cautioned that the death of the 39-year-old militant was not likely to end the bloodshed - just as the capture of Saddam Hussein and the killings of his two sons failed to dampen the insurgency. A rash of bombings that killed nearly 40 people in Baghdad on Thursday confirmed that assessment.

“We have tough days ahead of us in Iraq that will require the continuing patience of the American people,” Bush said.

Nevertheless, the president called the killing “a severe blow to al-Qaida, and it is a significant victory in the war on terror.”

Tips from within al-Zarqawi's own terror network helped the U.S. locate and bomb a safe house where the al-Qaida leader was meeting in secret with top associates, American military officials said. Al-Maliki told al-Arabiya television the $25 million bounty the U.S. put on al-Zarqawi's head would be honored, saying “we will meet our promise.”

Al-Zarqawi was killed at 6:15 p.m. Wednesday after an intense two-week hunt that U.S. officials said first led to the terror leader's spiritual adviser and then to him.