President Barack Obama has announced a plan to start withdrawing US troops from Afghanistan in a first step toward ending the long, costly war.

Obama said he would pull 10,000 troops from Afghanistan by year's end, followed by about 23,000 more by the end of next summer and a steady withdrawal of remaining troops after that.

In a 15-minute televised address, Obama vowed that the United States -- struggling to restore its global image, repair its faltering economy and bring down the high jobless rate at home -- would end a decade of military adventures prompted by the September 11 attacks in 2001 and exercise new restraint with American military power.

"Tonight, we take comfort in knowing that the tide of war is receding," Obama said, heralding the gradual drawdown of US forces in Iraq and the limited US involvement in the ongoing international campaign in Libya.

"America, it is time to focus on nation building at home."    

Yet news that Obama will pull the entire 'surge' force he sent to Afghanistan in 2010 is certain to fuel friction between Obama and his military advisors who have warned about the perils of a hasty drawdown.   

Nearly 10 years after the Taliban government was toppled, US and Nato forces have been unable to deal a decisive blow to the resurgent Islamist group. The Afghan government remains weak and notoriously corrupt, and billions of dollars in foreign aid efforts have yielded meager results.

Obama's decision on trimming the US force was a more aggressive approach than many expected. It went beyond the options offered by General David Petraeus, the outgoing commander of US and Nato troops in Afghanistan, whom Obama has picked to lead the CIA.

The president's decision reflected the competing pressures he faces as he seeks to curb spending and halt US casualties without allowing the threat of extremist attacks to fester.

Outgoing Defense Secretary Robert Gates said he supported Obama's decision. But the plan is unlikely to sit well with the Pentagon's top brass who worry insurgents could regain lost territory as fighting intensifies along Afghanistan's eastern border with Pakistan.

"We've undercut a strategy that was working. I think the 10,000 troops leaving this year is going to make this fighting season more difficult. Having all the surge forces leave by next summer is going to compromise next summer's fighting season," said Senator Lindsey Graham, a Republican member of the Senate Armed Services Committee.   

Even after the withdrawal of the 33,000 US troops, about 70,000 will remain in Afghanistan, about twice the number there when Obama took office.   

Reaction from the US Congress was mixed, as lawmakers impatient with a war that now costs more than $110 billion a year complained Obama should have embraced a larger drawdown. - Reuters