Washington, Sept 14: Under fire for the unpopular war in Iraq, President George W Bush has announced a gradual pullout of US troops from the country but rejected calls for a full withdrawal, arguing that abandoning its fledgling ally would embolden extremists and help the "destructive" ambitions of Iran.

Claiming success of his "surge" policy in reducing violence in the strife-torn country, Bush said he will pull out some 21,500 soldiers by July next year, which would leave around 1.3 lakh US troops in Iraq, roughly the same number just before the beginning of the increase in troop deployment last December.

"The principle guiding my decisions on troop levels in Iraq is: return on success. The more successful we are, the more American troops can return home," he said in a televised speech to the nation last night. Based on the advice of his top commander in Iraq, Bush said around 5,700 troops are expected to be withdrawn by Christmas. "And by July, we will be able to reduce our troop levels in Iraq from 20 combat brigades to 15," he said.