Obama aides defend ambitious Afghan scale-up

By Andrew Quinn and Phil Stewart

WASHINGTON (Reuters) - Top U.S. officials said the first of 30,000 new U.S. troops will arrive in Afghanistan in two to three weeks, but also made clear on Wednesday that plans to start bringing the soldiers home in 18 months could slip.

One day after President Barack Obama unveiled his high-risk strategy for the Afghan troop surge, Defence Secretary Robert Gates and Secretary of State Hillary Clinton faced scepticism from lawmakers of a big escalation of the unpopular and expensive war.

"This is a huge commitment. It's the right commitment. And it gives us the forces to turn this thing around," Admiral Mike Mullen, chairman of the military Joint Chiefs of Staff, told the House of Representatives Foreign Affairs Committee.

Obama's plan will bring the U.S. troop strength in Afghanistan to almost 100,000 in a buildup officials hope will secure the country after eight years of war and allow U.S. soldiers to start pulling out by the summer of 2011.

Defence Secretary Robert Gates, testifying at the Senate Armed Services Committee, said the first new U.S. forces would be sent in 2-3 weeks, starting an 18-24 month "extended surge".

Gates said the aim was to shift responsibility for security to the Afghans themselves. "Beginning to transfer security responsibility to the Afghans in summer 2011 is critical - and, in my view achievable," he said.

But U.S. commanders were keeping options open on the timing of a troop drawdown. Gates said they would review progress in December 2010 and final decisions on when to begin the withdrawal would depend on that assessment.

He said Washington would not abandon Afghanistan if the security situation appeared untenable. "We're not just going to throw these guys into the swimming pool and walk away," he said.