Both General David Petraeus and Admiral Mike Mullen, the chairman of the Joint Chiefs of Staff, said Obama's plan to withdraw 33,000 surge troops by the end of next summer was more "aggressive" than they had recommended.
Asked by Senator Carl Levin if he was prepared to resign over the war policy, Petraeus said: "I don't think it's the place for the commander to consider that kind of step unless you are in a very, very dire situation."
Petraeus, who indicated that he had received emails suggesting he should quit in protest, said: "This is an important decision, it is again a more aggressive approach than the chairman (Admiral Mullen), (Central Command chief General James) Mattis and I would have, indeed certainly, put forward.
|US President Barack Obama's (pictured, C) military commanders, General Favid Petraeus and Admiral Mike Mullen, have said he ignored their advice for a more modest drawdown from Afghanistan|
"But this is not something where one hangs up the uniform in protest or something like that."
The four-star general, who is due to step down in weeks as Obama's top commander in the fight against the Taliban-led insurgency and take over as CIA director, is credited by many as having salvaged the war in Iraq.
His testimony in Congress provided more ammunition to Obama's critics on the right who accuse the president of approving an overly hasty withdrawal plan for political motives ahead of presidential elections in 2012.
Defense Secretary Robert Gates, in an interview with AFP, endorsed Obama's plan but acknowledged that waning political support for the grinding counter-insurgency campaign was an important factor in the decision.
The "advantages and disadvantages" of a range of options were debated at three White House meetings, including "not only the situation on the ground in Afghanistan but also political sustainability here at home," Gates said.
He suggested Petraeus had advocated a slower timetable with more troops in place through next summer's fighting season.
"Obviously he had preferred options that gave more time," said Gates, who according to some reports brokered the compromise drawdown plan.
The military's top officer, Mullen, offered a qualified endorsement of Obama's decision, telling lawmakers that he had initially favored a more modest drawdown.
Mullen said "the president's decisions are more aggressive and incur more risk than I was originally prepared to accept."
But he said that keeping more forces in place also carried risks, including enabling Kabul to become more dependent on the American military presence.
"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.
Both Mullen and Petraeus said the president had to take into account other considerations beyond military conditions, a clear reference to political and fiscal pressures.
The American public is increasingly impatient with a war that has dragged on nearly a decade. In a new Pew Research Center poll, 56 percent of respondents -- the highest ever -- said American troops should be brought home as soon as possible.
White House officials insist Obama's move was based on military strategy -- not politics -- and that progress on the battlefield and the killing of Al-Qaeda leader Osama bin Laden had made the drawdown possible.
Petraeus promised the military nevertheless would carry out Obama's plan, saying it is "the responsibility, needless to say, of those in uniform to salute smartly and to do everything possible to execute it."