The president addressed the nation Wednesday night, saying the initial drawdown will involve 10,000 troops - 5,000 will come home this summer and 5,000 will come home by the end of the year. Another 20,000 troops will come home by September 2012.
That still will leave a force of about 70,000 in the country and the White House is indicating that U.S. forces will remain in Afghanistan for years.
"After this initial reduction, our troops will continue coming home at a steady pace as Afghan security forces move into the lead," said Obama. "Our mission will change from combat to support. By 2014, this process of transition will be complete, and the Afghan people will be responsible for their own security."
At least 1,500 members of the U.S. military have died and 12,000 have been wounded since the war began in late 2001.
Reaction to the drawdown in Washington is mixed. Some members of the president's own party say not enough troops are coming home fast enough.
"It has been the hope of many in Congress and across the country that the full drawdown of U.S. forces would happen sooner than the president laid out - and we will continue to press for a better outcome," said House Minority Leader Nancy Pelosi (D-Calif.).
Some Republicans said they believe the drawdown is too fast.
"This is not the 'modest' withdrawal that I and others had hoped for and advocated," Sen. John McCain (R-Ariz.) said in a statement.
Many military families who gathered in Llong Beach to watch the president's speech left disappointed. They said the timetable means tens of thousands of troops won't be coming home for a very long time. That could mean more suffering for the troops and their families.
"I was hoping for more," said Rossana Cambron, a mother of a U.S. soldier.
Another mother, Pat Alviso, said she's "very disappointed" in the plan.
"I voted for this president, and when the surge started, it was just the worst thing for us," Alviso said.
An Exclusive Eyewitness News poll conducted by SurveyUSA asked Californians: Is the president withdrawing troops too fast? Not fast enough? Or is the president's timetable just right?
Twenty-three percent said too fast, 34 percent said not fast enough, 39 percent said the timetable is just right and 5 percent said not sure.
People were also asked: Do you approve or disapprove of the way President Obama is handling the situation in Afghanistan?
Forty-four percent said they approve, 43 percent disapprove and 13 percent are not sure.
The Associated Press contributed to this report.