Iraq's prime minister said the end of US combat operations on Tuesday restored Iraq's sovereignty and meant it stood as an equal to the United States, despite political deadlock and persistent violence.

US troop levels were cut to 50,000 before the partly symbolic deadline of Aug 31 set by President Barack Obama to fulfil his pledge to end the war launched by his predecessor George W Bush.   

The six remaining US brigades will turn their focus to training Iraqi police and troops as Iraq takes charge of its own destiny ahead of a full US withdrawal by the end of next year.

"Iraq today is sovereign and independent," Prime Minister Nuri Al-Maliki told Iraqis in a televised address to mark the US forces' shift to assisting rather than leading the fight against a Sunni Islamist insurgency and Shi'ite militia.

"With the execution of the troop pullout, our relations with the United States have entered a new stage between two equal, sovereign countries."    

Obama promised war-weary US voters he would extricate the United States from the war, launched by Bush with the stated aim of destroying Iraqi weapons of mass destruction. No such weapons were found. Almost a trillion dollars have been spent and more than 4,400 US soldiers and over 100,000 Iraqi civilians killed since the 2003 invasion.

Obama's Democrats are battling to retain control of Congress in November elections and he faces other challenges -- a worsening war in Afghanistan and storm clouds over the economy.   

Tuesday's deadline was to some extent a symbolic one. The 50,000 US soldiers staying on in Iraq for another 16 months are a formidable and heavily-armed force.

Iraqi security forces have already been taking the lead since a bilateral security pact came into force in 2009. US soldiers pulled out of Iraqi towns and cities in June last year.

Nevertheless, Iraqis are apprehensive as US military might is scaled down, especially amid a political impasse six months after an inconclusive election.

"We'll be just fine, they'll be just fine," US Vice President Joe Biden said after flying into Baghdad on Monday to mark the end of combat operations and to urge Iraqi leaders to speed up the formation of a new government.

"Notwithstanding what the national press says about increased violence, the truth is things are very much different. Things are much safer," Biden told Al Maliki on Tuesday before their meeting was closed to the media.

Toppled dictator Saddam Hussein's outlawed Baath party crowed that the US pullback was a result of "devastating" strikes against US troops by Iraqi resistance fighters.   

"They withdrew dragging tails of failure and defeat, leaving by the same roads they used as invaders," it said in a statement carried by Iraqi websites. "The end of the US combat mission  in Iraq is a useless attempt to save face, if any is left."

US officials said Washington had a long-term commitment to Iraq, and the military pullback would allow diplomats to take the lead in building economic, cultural and educational ties. For that they need a new Iraqi government to be in place.   

Violence has declined sharply since the peak in 2006/07 of the sectarian slaughter unleashed by the invasion, but a recent series of attacks has rung alarm bells.
 The animosity that led to carnage between majority Shi'ites and once dominant Sunnis has not healed, and a potentially explosive dispute between Arabs and Kurds has not been resolved.

More than 1.5 million Iraqis are still displaced after being driven from their homes by violence. Many live in squalor. - Reuters