President Bush told Americans yesterday he would send over 20,000 more US troops to halt Iraq's collapse into civil war.
US President George W Bush
"To step back now would force a collapse of the Iraqi government, tear that country apart and result in mass killings on an unimaginable scale," Mr Bush said in a televised address, responding to calls for him to start a gradual withdrawal.
But many Iraqis - and the president's opponents in Congress - were sceptical the increase could do much good.
As voters questioned the value of adding to the 3,000 US troops killed in Iraq, Mr Bush said the Iraqi government must keep promises to rein in militants on all sides to retain his backing - restating a condition some analysts see as pre-emptively shifting responsibility for any future failure to end bloodshed.
"America's commitment is not open-ended," said Mr Bush, whose own term, indelibly marked by the Iraq war, ends in two years.
"If the Iraqi government does not follow through on its promises it will lose the support of the American people," he said, making a rare acknowledgment of past errors. "The year ahead will demand more patience, sacrifice and resolve."
Prime Minister Nuri al-Maliki has vowed to lead the new Baghdad security operation and said it will strike not only insurgents from Saddam Hussein's once dominant Sunni minority but also militias loyal to fellow Shias - a key demand of Washington and Sunnis, who say Iran is backing Shia gunmen.
Responses to the latest plan highlighted sectarian divides, with Sunnis hoping for the best and many Shias increasingly resentful of the presence of the Americans who overthrew Saddam.
Mr Bush renewed complaints about the role of Syria and Shia Iran in Iraq, and US troops raided an Iranian consular office in the Iraqi Kurdish city of Arbil overnight, arresting five Iranians in the second such operation in the past month.
In Sadr City, the Baghdad slum bastion of the Mehdi Army militia led by Shia cleric Moqtada al-Sadr, residents said US and Iraqi troops staged an overnight raid on militants.
Such raids are not uncommon but Sunni leaders complain - as US commanders have done - that not enough effort was made last year to strike Shia groups blamed for some of the death squad killings.
Baghdad police found 60 bodies around the city yesterday, and many thousands have fled their homes.