All US combat troops will leave Iraq by August next year and a full withdrawal will be completed by the end of 2011 under a strategy to be laid out Friday by President Barack Obama, top officials said. Obama, an early opponent of the US-led 2003 invasion, will fulfill his campaign promise to withdraw US troops slightly behind schedule. There are currently about 142,000 US troops in Iraq but the conflict -- in which more than 4,250 US troops have died -- has deeply divided the US public and badly hit the United States' international standing. Obama will set out the withdrawal deadlines in a speech at Camp Lejeune, a major US Marine base in North Carolina. He will announce that "our combat mission will end on August 31, 2010," a senior US official told reporters, speaking on condition of anonymity. "At that point, the US forces remaining in Iraq will undertake a new mission, a more limited mission, that will be focused on three specific areas," the official said. This would be to "train, equip, and advise the Iraqi security forces," to protect US civilian personnel in Iraq, and to conduct "targeted counter-terrorism operations on its own and in conjunction with the Iraqi forces," the official said.