FACTBOX: U.S. military "surge" in Iraq troop level

(Reuters) - Gen. David Petraeus, the top U.S. commander in Iraq, and Ambassador Ryan Crocker update Congress on Tuesday on progress made during a "surge" of force in the war zone credited with helping to reduce violence. Here are facts about the surge strategy and its goals.

SURGE STRATEGY

President George W. Bush ordered the U.S. military to increase troop levels in Iraq in January 2007 under a strategy known commonly as the "surge" that included security, political, economic and regional components.

--Five brigade combat teams, including about 20,000 combat troops and another 10,000 support personnel, were sent to Iraq from February to mid-June. The Pentagon also requested Congress to increase the total size of the Army and Marine Corps to help ease the strain on the force from the Iraq war.

--Iraq agreed to deliver additional Iraqi forces to Baghdad and to bar political officials from interfering with security operations.

--The aim of the surge was to help Iraqi soldiers reduce sectarian violence and create what Bush called "breathing space" for Iraqi officials to make progress on legislative initiatives seen by Washington as critical to long-term stability.

GOALS FOR THE IRAQI GOVERNMENT:

--Take responsibility for security in all of Iraq's provinces by November 2007

--Give U.S. and coalition forces authority to pursue all extremists

--Pass legislation to share oil revenues among all Iraqis and promote investment

--Reform de-Baathification laws

--Hold provincial elections in 2007

PROGRESS TOWARD GOALS

--Attacks in Iraq declined 60 percent during the surge, according to the U.S. military. Deaths from sectarian violence dropped 90 percent after the last additional U.S. combat brigade arrived in Iraq in June 2007. But violence has climbed in 2008 due to al Qaeda activity in the north and intra-Shi'ite violence in the south.

--Iraq has taken security responsibility for half of its 18 provinces. A Pentagon report to the U.S. Congress in September said the handover of security responsibility for all provinces could be complete by July 2008, past the November 2007 target.

--Legislation to share Iraq's oil revenue equitably among Iraqis and to clear the way for investment in its oil fields has been deadlocked by a battle for control of the reserves.

--Iraq enacted the "Accountability and Justice Law" in January, which became law in February, to allow the majority of former members of Saddam Hussein's Baath party to return to former posts in government.

--Iraq enacted the "Provincial Powers Law" in March to pave the way for provincial elections. It will define the relationship between Iraq's 18 provinces and the central government and is seen by Iraqi officials as a first step toward provincial elections, due by October.

(Writing by Kristin Roberts; Editing by Eric Walsh)