The top US military officer said on Thursday that he endorsed President Barack Obama's Afghan withdrawal plan despite initial worries about the risks of "sacrificing fighting power in the middle of a war."
"More force for more time is, without a doubt, the safer course. But that does not necessarily make it the best course," US Joints Chiefs chairman Admiral Mike Mullen told the House Armed Services Committee.
"There is no jumping ship here. Quite the contrary. We will have at our disposal the great bulk of the surge forces through this -- and most of the next -- fighting season," Mullen said one day after Obama unveiled his strategy.
The president, facing a war-weary public as he chases re-election in 2012, announced Wednesday after consultations with his national security team that he was ordering all 33,000 US surge troops home from Afghanistan by next summer.
Mullen said he did not wish to discuss his "private advice" in the matter, but told lawmakers "the president's decisions are more aggressive and incur more risk than I was originally prepared to accept."
"Only the president, in the end, can really determine the acceptable level of risk we must take. I believe he has done so," he said.
Peppered with questions, Mullen said US commanders would have flexibility "inside the numbers and the dates" on the number and kind of troops who would go home and disputed claims US gains in the war were "easily reversible."
"I disagree that the gains will be easily reversed," said Mullen, who allowed that progress on the political and security fronts in Afghanistan only becomes "irreversible" if Afghans step up and take charge of their fate.
"The truth is, we would have run other kinds of risks by keeping more forces in Afghanistan longer," including Kabul's increased "dependency" on the US presence, he said.
"Let me be candid, however. No commander ever wants to sacrifice fighting power in the middle of a war. And no decision to demand that sacrifice is ever without risk," he warned.
The committee's chairman, Republican Representative Buck McKeon, said he was "deeply concerned" that Obama's approach endangered "hard-won" gains in a conflict sparked by the September 11, 2001 terrorist strikes.
"These gains are significant, we should guard them jealously," he said. "I am concerned that we will withdraw combat forces before they are able to cement recent gains."
But Undersecretary of Defense Michele Flournoy, appearing with Mullen, underlined to the committee that there would still be some 68,000 US troops in Afghanistan after some 33,000 return home by the end of next summer.
"That's more than twice the number as when President Obama took office. Clearly, this is not a 'rush to the exits' that will jeopardise our security gains," she said.
"We have earned this opportunity. Though not without risk, it is also not without its rewards. And so, we will take that risk, and we will reap those rewards," said Mullen.