President George W. Bush said the decision to move troops into Basra is confirmation of Prime Minister Nouri al-Maliki's leadership capabilities.

The president's comments at a White House news conference with Australian Prime Minister Kevin Rudd followed U.S. airstrikes in both the southern city of Basra and in a Shiite militia stronghold in Baghdad.

"Basra has been a place where criminality has thrived," Bush said. "They are fighting some pretty tough characters and yes, there's going to be violence, and that's sad."

Bush said the resurgent violence would not alter his administration's mission in Iraq.

"Any government that presumes to represent the majority of people must confront criminal elements or people who think they can live outside the law. That's what's taking place in Basra and other parts of Iraq," Bush said. "I would say this is a defining moment in the history of Iraq."

The president said the situation in Iraq remains "dangerous and fragile," but says the resurgent violence will not alter his determination to continue his administration's mission there.

"I'm confident we can succeed unless we lose our nerve," he added. "It's going to take a while for them to deal with these elements. "

Friday's air raid is the first since clashes erupted this week between Shiite militias and government security forces in the southern oil port city.

The British official said Iraqi security forces asked for airstrikes on at least two locations. There was no word on casualties or the nature of the targets.

Coalition jets have been patrolling the skies over Basra for the past three days.

Iraqis have been in control of security there since the British withdrew last December.

Iraqi police said clashes between Shiite militants and government security forces resumed Friday in at least two cities south of Baghdad.

The fighting in Nasiriyah and Mahmoudiya Friday comes as the fighting calmed down in Baghdad.

Residents were holed up in their homes because of a weekend curfew.

Police said four people have been killed and 14 wounded in clashes in Nasiriyah.

Anger has been growing since the Iraqi government launched a crackdown against Shiite militia violence in Basra earlier this week.

Shiite cleric Muqtada al-Sadr's followers said security forces are abusing a cease-fire by his Mahdi Army militia to unfairly target them in raids.

The government said it is acting against criminal gangs.

The government of Iraq is giving people in the southern city of Basra until April 8 to surrender what are described as "heavy and medium-size weapons."

A government adviser said people who comply will get an unspecified amount of money as a reward.

Friday's ultimatum by Prime Minister Nouri al-Maliki is separate from the three-day ultimatum he laid down for Shiite gunmen in the city to surrender their weapons and renounce violence or face harsh consequences.

That deadline is Friday.

It's common for even noncombatants in Iraq to have machine guns and even grenade launchers.

Green Zone Fighting

On Thursday, the U.S. Embassy in Baghdad said advisories and restrictions telling U.S. diplomats in the Iraqi capital to "stay under hard cover" would be in place until further notice.

The State Department said in a memo that employees were required to wear helmets and other protective gear if they must venture outside even in the heavily fortified Green Zone and strongly advises them to sleep in blast-resistant locations instead of the less secure trailers that most occupy.

"Due to the continuing threat of indirect fire in the International Zone, all personnel are advised to remain under hard cover at all times," it said. "Personnel should only move outside of hard cover for essential reasons."

The memo came after two American government workers were killed this week.