Iraq War Commander: Military Alone Won't Win

As additional U.S. troops continue to flow into Baghdad, the new U.S. commander in Iraq, Gen. David Petraeus, warned that force alone would not get the job done.

"Any student of history knows there is no military solution to a problem like that in Iraq, to the insurgency of Iraq," said Petraeus. "Military action is necessary to help improve security … but it is not sufficient."

Watch Jonathan Karl's report on Gen. Petraeus' remarks tonight on "World News."

But in his first public comments since taking over, Petraeus made it clear the surge of more than 20,000 additional combat troops won't be over any time soon. After all, he said, all those troops won't even be in place until this summer.

"This is months; this is not days, it's not weeks, it is months," he said. "It will be all the way until early June before we even have all the force in position."

Petraeus' deputy, Gen. Ray Odierno, is now recommending that the surge last at least until February 2008, possibly putting the commanders in Iraq on a collision course not only with the Democrats in Congress, who are proposing a bill to require that a pullout begin soon afterward, but also with the Joint Chiefs of Staff.

ABC News has learned military planners at the Pentagon have recommended the drawdown of those forces begin in September. The reason is that they believe stress on the Army is simply too great to maintain higher force levels any longer than that.

But commanders in Iraq say even with the strain on the Army, there is simply no choice.

"It would have been unrealistic to expect the surge could accomplish in six months or less what we haven't been able to succeed [at] in the past four years," said Bruce Hoffman, a professor in the Security Studies Program at Georgetown University's Edmund A. Walsh School of Foreign Service.

But the Baghdad plan is now extending beyond Baghdad. ABC News has learned that U.S. forces recently seized an al Qaeda document that shows insurgents plan to use the towns around Baghdad as staging areas to wage attacks on the city.

Petraeus today did not rule out asking for even more troops down the road. He said there are no immediate requests, but that he would not hesitate to ask for more if needed.

ABC News' Jon Karl originally reported this story for "World News."