Staff Sgt. Nathan Brooks, 25, from Vergennes, Ill., stands guard on a rooftop Monday as Iraqi women watch soldiers from Delta Company, 4th Battalion, 31st Infantry Regiment, 2nd Brigade, 10th Mountain Division search their home nine days after an attack that left four U.S. soldiers and an Iraqi soldier dead and three comrades missing in Quarghuli village south of Baghdad.

Baghdad, Iraq ? Iraq’s military is drawing up plans to cope with any quick U.S. military pullout, the defense minister said Monday, as a senior American official warned that the Bush administration may reconsider its support if Iraqi leaders don’t make major reforms by fall.

The U.S. official did not say what actions could be taken by the White House, but his comments reflected the administration’s need to show results in Iraq – as an answer to pressure by the Democrats in Congress seeking to set timetables on the U.S. military presence.

Several mortar shells hit the U.S.-controlled Green Zone, one striking the Iraqi parliament building but causing no casualties – the latest in near daily barrages on the nerve center of the U.S. mission and Iraqi government that underline the country’s tenuous security.

At least 58 Iraqis were killed by attacks or found dead across Iraq, including seven people ambushed on a bus northeast of Baghdad, police said. The dead included 24 men whose bullet-riddled bodies were found across Baghdad, apparent victims of sectarian death squads.

British troops clashed with Shiite Muslim gunmen in the southern city of Basra. Britain’s military said one British soldier and a civilian driver were killed when a supply convoy was attacked in the center of the city, Iraq’s second biggest.

Elsewhere, U.S. troops raided safe houses south of Baghdad but failed to find three soldiers missing since a May 12 ambush that left four other Americans and an Iraqi dead.

“We’ve (identified) some safe houses and we targeted a couple of those today and they were able to slip away from us. But we’re going to come at things from a different angle,” a U.S. spokesman, Maj. Webster Wright, said without elaborating.

U.S. officers said the search by thousands of U.S. and Iraqi soldiers may be forcing the kidnappers to move the three Americans frequently, preventing insurgents from posting pictures of their captives on the Internet.

“We choose to be cautiously optimistic,” Maj. Gen. Rick Lynch told CNN. “We’re pursuing all leads with a passion, but right now we believe our soldiers are still alive. Each day that passes when we don’t see proof of life, it causes us concern.”

With violence raging, pressure is mounting on Prime Minister Nouri al-Maliki’s government to demonstrate progress on key reforms or risk losing American support for the unpopular war.

On Monday, Defense Minister Abdul-Qader al-Obeidi told reporters Iraq’s military was drawing up plans in case U.S.-led forces left the country quickly.

“The army plans on the basis of a worst case scenario so as not to allow any security vacuum,” al-Obeidi said. “There are meetings with political leaders on how we can deal with a sudden pullout.”

It was unclear whether al-Obeidi’s comment referred to routine contingency planning or reflected a feeling among Iraqi leaders that the days of U.S. support may be numbered even though President Bush blocked an effort by Congress to set a withdrawal timetable.

A White House spokesman, Tony Fratto, said President Bush expressed confidence in al-Maliki during a telephone call Monday to the Iraqi leader.

He said the two talked about political progress in Iraq, and al-Maliki gave Bush updates on two key U.S. demands – legislation to share Iraq’s oil wealth among its regions and ethnic groups and a reform of the constitution.

But two senior Iraqi officials told The Associated Press that Bush warned al-Maliki that Washington expected to see “tangible results quickly” on the oil bill and other legislation as the price for continued support.

The officials spoke on condition of anonymity because they weren’t supposed to release the information.