Afghan officials are welcoming the announcement by President Barack Obama that half of America's 66,000 troops in Afghanistan will be brought home within a year.

But the news is being greeted with dismay by some Afghans who say America failed to keep its promise to give them a better and safer life.

A troop draw-down had been widely expected. But for the first time, Obama said how many would leave.

Afghan President Hamid Karzai viewed the announcement as good news. He has pushed for a faster pullout of international troops, arguing that his country is sovereign and should control its own fate.

But some Afghans said they were taken aback that so many Americans would leave even before next year's deadline. Persistent violence and a spate of insider attacks by Afghan troops against their foreign partners have raised concern about the readiness of government forces to take over their own security.