BAGHDAD-- 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. U.S. troop levels were cut to 50,000 before the partly symbolic deadline of August 31 pledged by President Barack Obama to fulfil his pledge to end the war launched by his predecessor George W. Bush. The six remaining U.S. brigades will turn their focus to training Iraqi police and troops as Iraq takes charge of its own destiny ahead of a full U.S. 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 U.S. 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 U.S. 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 U.S. 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.