FACTBOX: Iraq's recent security operations

(Reuters) - Iraqi security forces launched a major operation against Shi'ite militias in the southern city of Amara on Thursday. The offensive is the latest in a series of military campaigns by Prime Minister Nuri al-Maliki that are intended to stamp the government's authority over areas once controlled by Shi'ite militias or Sunni Arab al Qaeda militants.

Following is a factbox on Iraq's recent security operations:

WHY AMARA?

Amara, home to about 250,000 people, is a stronghold of anti-American Shi'ite cleric Moqtada al-Sadr, whose Mehdi Army militia has been the target of recent crackdowns in the southern oil hub of Basra and the capital Baghdad.

Amara is also the capital of Maysan province, a haven for arms smugglers from neighboring Iran. Maysan is an oil-rich but poor region that was controlled by British forces for four years after the 2003 U.S.-led invasion of Iraq.

Maliki had given "outlaws" and "criminals" four days to surrender and hand over heavy weapons and bombs. Sadr has sent orders to the Mehdi Army not to resist and Maliki's office said on Tuesday he has ordered security forces not to detain Sadr supporters in Amara simply because they are affiliated with the faction. Amara lies 300 km (185 miles) southeast of Baghdad.

OPERATIONS BEGAN IN BASRA

In late March, Maliki launched an offensive in the southern city of Basra, the hub for nearly all Iraq's oil exports. The offensive caught U.S. officials in Baghdad off-guard and got off to a rocky start when the Mehdi Army resisted fiercely. Iraqi troops had to call for U.S. air and ground support. Around 1,000 Iraqi soldiers deserted. Iraqi troops took control of Basra within a week after Sadr told his militia to stop fighting. Despite questions the operation raised about the capabilities of Iraq's armed forces, Maliki won support from politicians across the country's ethnic and sectarian divide for cracking down on Shi'ite militias. The prime minister himself is Shi'ite.

BATTLES RAGE IN BAGHDAD'S SADR CITY

The Basra crackdown sparked clashes in the Mehdi Army stronghold of Sadr City in eastern Baghdad that lasted for seven weeks. Hundreds of people were killed in fighting between militiamen and U.S.-backed security forces. A truce agreed between Shi'ite factions in mid-May ended the fighting. Later that month 10,000 Iraqi soldiers moved into Sadr City unopposed. This allowed the government to impose its authority in an area generally outside its control since Maliki took office two years ago. The Iraqi army's movement in Sadr City has been coordinated with Sadr's office to avoid bloodshed. U.S. troops have stayed on the perimeter of Sadr City.

AL QAEDA TARGETED IN MOSUL

Maliki had been promising a major assault against al Qaeda in Iraq militants in the northern city of Mosul since the start of the year. The U.S. military has described the city, Iraq's third largest, as al Qaeda's last major urban stronghold. The scale of operations in Mosul picked up in mid-May when Maliki flew to Mosul for several days. Major-General Mark Hertling, the commander of U.S. forces in northern Iraq, said in late May that U.S. and Iraqi troops had inflicted serious damage on al Qaeda in Mosul. Iraqi security officials say the group's network has been broken in the city.

WHAT HAS BEEN THE IMPACT OF THE OPERATIONS?

The operation in Basra initially sparked a sharp spike in violence and raised the specter of a full-scale uprising by the tens of thousands of members of the Mehdi Army. But with Basra and Baghdad's Sadr City under control, and security forces putting the squeeze on al Qaeda in Mosul, violence in Iraq has fallen to a four-year low. The Iraq-led operations underscore the Shi'ite-led government's desire to take more control of security from the 150,000 U.S. troops in Iraq. Beyond the security gains, the operations have helped Maliki boost his image ahead of provincial elections due to be held on Oct 1. Maliki has said the crackdown on Shi'ite militias proved his government was not sectarian.