In his weekly radio and Internet address, the president said the United States' "core objective -- the reason we went to war in the first place -- is now within reach: ensuring that al-Qaida can never again use Afghanistan to launch attacks against America."
He said he and Afghan President Hamid Karzai agreed in their White House meeting Friday "this spring Afghan forces will take the lead for security across the entire country, and our troops will shift to a support role."
"In the coming months, I'll announce the next phase of our drawdown," he said. "And by the end of next year, America's war in Afghanistan will be over."
Obama said the mission in Afghanistan remains a "very difficult mission" and U.S. forces "are still in harm's way."
"But make no mistake -- our path is clear, and we are moving forward," he said. "Because after more than a decade of war, the nation we need to rebuild is our own."
Obama said the United States needs to provide proper care for military troops and veterans and also must "grow our economy and shrink our deficits," create jobs and increase Americans' incomes.
"We have to fix our infrastructure and our immigration system," the president said. "We have to protect our planet from the destructive effects of climate change -- and protect our children from the horrors of gun violence.
"These, too, will be difficult missions for America," he said. "But they must be met. And if we can summon just a fraction of the determination of our men and women in uniform, I know we can meet them."