WASHINGTON - The chairman of US Joint Chiefs of Staff, Admiral Michael Mullen, said on Thursday that President Barack Obama's decisions on military drawdown from Afghanistan "incur more risk" than he was initially prepared to accept.

Mullen made the remarks while testifying before the House of Representatives Armed Services Committee, one day after Obama announced a faster-than-expected drawdown of American military forces from Afghanistan.

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"What I can tell you is, the president's decisions are more aggressive and incur more risk than I was originally prepared to accept," Mullen said, though he also said he endorsed those decisions.

"More force for more time is, without doubt, the safer course," he said. "But that does not necessarily make it the best course. Only the president, in the end, can really determine the acceptable level of risk we must take."

Under Obama's plan, 10,000 troops will be pulled out from the country by year end, and a total of 33,000 troops will be out by next summer, fully recovering the surge troops the president announced in late 2009. The pace of the drawdown is much faster than some Pentagon officials and military commanders would like to see, as they have been lobbying hard for a "modest" withdrawal so as not to compromise security there.

Still, Pentagon officials expressed endorsement for the plan, saying it is consistent with US Afghan strategy.

"This announcement in no way marks a change in American policy or strategy in Afghanistan," Undersecretary of Defense Michele Flournoy said at the House hearing. "Clearly, this is not a 'rush to the exits' that will jeopardize our security gains."

Immediately after the president's announcement, Defense Secretary Robert Gates issued a statement voicing support for the decision, saying "it provides our commanders with enough resources, time and, perhaps most importantly, flexibility to bring the surge to a successful conclusion."