US President Barack Obama said Saturday that the US goal in Afghanistan was "within reach" as he vowed to move ahead with a timetable to end the 11-year-old military campaign and focus on a broad domestic agenda.

"We've pushed the Taliban out of their strongholds," Obama said in his weekly radio and Internet address. "And our core objective -- the reason we went to war in the first place -- is now within reach: ensuring that Al-Qaeda can never again use Afghanistan to launch attacks against America."

The comments came after Obama wrapped up talks with visiting Afghan President Hamid Karzai, promising to speed up a transfer of lead security responsibility from NATO to Afghan forces this spring, in a sign that the pace of US troop withdrawal could quicken.

After meeting with Karzai, Obama said NATO forces would have a "very limited" role in the country after 2014 and insisted that Washington had achieved its prime goal of "decapitating" Al-Qaeda.

The leaders met at a crucial moment in the final chapter of a long, bloody war, and as Obama balances the future security of Afghanistan with US combat fatigue and a desire to spend America's dwindling resources at home.

Obama, planning the withdrawal of most of the 66,000 US troops left in Afghanistan, said that after 2014, American forces would have a "very limited" mission in training Afghan forces and preventing a return of Al-Qaeda.

"This week, we agreed that this spring, Afghan forces will take the lead for security across the entire country, and our troops will shift to a support role," the US president said. "In the coming months, I'll announce the next phase of our drawdown. And by the end of next year, America's war in Afghanistan will be over."

Obama said that now Americans faced difficult domestic tasks of taking care of returning veterans, growing the economy, shrinking budget deficits, creating new jobs and boosting family incomes.

"We have to fix our infrastructure and our immigration system," he noted.

"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. But they must be met."

The White House has ordered the Pentagon to come up with plans for a smaller future Afghan presence than generals had expected, perhaps numbering 3,000, 6,000 or 9,000 US troops.

Obama's domestic political opponents, however, charge he is in a rush for the exit and warn that a minimal force could squander gains hard won in a war that has killed more than 3,000 coalition troops.

The White House even suggested this week that Obama would not rule out the possibility of leaving no American boots on the ground.

This has compounded Afghan fears that the country could be abandoned again by the international community -- as it was after the end of the Soviet occupation in 1989.

The power vacuum led to the rise of the Taliban, and a safe haven for Al-Qaeda to plot the September 11 attacks, which drew the United States into an Afghan war in 2001.

Obama said Friday that despite the huge human and financial cost of the 12-year war, it was important to recognize that it had been waged in response to those attacks and had achieved its central goals.

"There is no doubt that the possibility of peace and prosperity in Afghanistan today is higher than before we went in," he said.

"Have we achieved everything that some might have imagined us achieving in the best of scenarios? Probably not. You know, there is a human enterprise, and you fall short of the ideal."

But the US president warned that Karzai, with whom he has had a somewhat testy relationship, would have to accept a security agreement, still under discussion, granting legal immunity to US troops who remain behind.

Karzai pledged he would stand down at the end of his second term, after elections in 2014, amid some concern that he could try to cling to power.

"The greatest of my achievements eventually, seen by the Afghan people, will be a proper, well-organized, interference-free election in which the Afghan people can elect their next president," he said.

"And certainly I will be a retired president, and very happily a retired president," the two-term Afghan leader vowed.