Influential Sunni scholars encouraged Iraqis to join the country's security forces and protect the country, issuing an edict Friday that departed sharply from earlier warnings against participating in the fledgling police and army.

Also Friday, an explosion damaged a ninth-century, spiral minaret that is one of Iraq's most recognized landmarks. The blast in the central city of Samarra (search) blew a large hole in the structure, police Lt. Qasim Mohammed said.

Witnesses said two men climbed the 170-foot-tall minaret, then returned to the ground before the explosion occurred. The minaret is a symbol of Samarra's past glory, the only remains of a mosque dating back from the Abbasid Islamic dynasty. It is featured on Iraq's 250-dinar bill.

It was unclear why the minaret was targeted. U.S. troops have used its top as a sniper position, and last year, the Islamic extremist group linked to Jordanian terrorist Abu Musab al-Zarqawi (search) flew a flag from its peak.

Sgt. Brian Thomas, a spokesman for the 42nd Infantry Division, said coalition forces no longer used the minaret. He said Iraqi police were investigating the explosion.

Friday's edict, endorsed by a group of 64 Sunni clerics and scholars, instructed enlistees to refrain from helping foreign troops against their own countrymen.

But Ahmed Abdul Ghafour al-Samarrai, a cleric in the influential Association of Muslim Scholars (search) who read the edict during a sermon at a major Sunni mosque, said joining the Iraqi security forces was now necessary to prevent the country from falling into "the hands of those who have caused chaos, destruction and violated the sanctities."

If heeded, the announcement could strengthen Iraqi security forces, who are trying to take over the fight against the Sunni-led insurgency. It came as Ukraine and Italy gave timelines to pull troops from Iraq later this year, further dwindling the number of U.S.-led coalition forces.

In ongoing violence against Iraq's faithful, a bomb near a Sunni mosque in Kirkuk killed one civilian heading to Friday prayers, said police official Sarhat Qadir. Three others were also injured.

In the holy city of Karbala, Shiite pilgrims began leaving after sleeping on city streets because they feared traveling at night after a string of attacks on pilgrims. Bus stations were packed with faithful heading home after a Shiite religious holiday marking the end of a 40-day mourning period for Imam Hussein, grandson of the Prophet Muhammad and one of Shiites' most important saints.

Fighters from the Sunni Muslim-led insurgency staged several deadly attacks on Shiite pilgrims in the days leading up to the religious festival. Security measures remained in place Friday, with policemen keeping watch from building rooftops and patrolling the streets.

Also Friday, witnesses said a car bomb exploded outside a U.S. base in Ramadi, near a convoy at the base's gate. The U.S. military and Iraqi police did not immediately have information on the blast.

In the eastern city of Balad Ruz, gunmen killed police chief Col. Hatim Rashid and another officer at a police station, police Col. Mudhafar al-Jubouri said.

Ukrainian President Viktor Yushchenko (search) said his country's troops will leave Iraq by year's end. Ukraine had already said it would begin pulling out its 1,650 soldiers, the fifth-largest contingent in the coalition, but had not set a timetable.

Italian Premier Silvio Berlusconi also said he plans to trim his contingent of troops at the end of September by about 300 soldiers from his current force of 3,300.

In Romania, which has 800 soldiers in Iraq, Prime Minister Calin Popescu Tariceanu refused to say whether he would consider withdrawing his country's troops after kidnappers released a video showing three Romanian journalists who were abducted in Baghdad.

The video, aired by Al-Jazeera satellite television, showed the three Romanian journalists and a fourth unidentified person — possibly an American — with guns pointed at them. Tariceanu said no demands had been made yet.

The troop reduction announcements came as U.S. forces have intensified programs to train more troops in the Iraqi Army and police force, hoping to stabilize the country with native forces.