The flag of American troops in Iraq has been ceremonially lowered in Baghdad, bringing nearly nine years of US military operations in Iraq to a formal end. The US Defence Secretary, Leon Panetta, told soldiers the mission had been worth the cost in blood and dollars. Only about 4,000 US soldiers now stay in Iraq, but they are due to leave in the next two weeks. At the peak of the mission, US troops there numbered 170,000, Bbc.co.uk reported.