The leaders announced in a joint statement that the military mission would shift from combat to support in the spring. That was originally expected to take place in the summer.
"Our role is clear," Obama said. "Everyday, Afghans are standing up to take control of their security, and as they do our troops will come home."
Obama and Afghan President Hamid Karzai announced that, by spring, most unilateral US combat operations should come to an end, with forces pulling back their patrols of Afghan villages.
"I am very happy to hear from the president, as we also discussed earlier, that in spring this year the Afghan forces will be fully responsible for providing security to the Afghan people," Karzai said.
Obama emphasized that the time was right for US forces to let Afghans do their own fighting in a radio address and internet address on Saturday.
The leaders also discussed the possibility of US troops in Afghanistan beyond 2014, the set date for a withdrawal. They did not specify how many troops might remain, with the White House earlier this week leaving open the possibility of withdrawing all US forces from the country after more than 10 years of war.
mkg/dr (AP, dpa)