The nation's top military officer warned Tuesday that an effective counterinsurgency in Afghanistan "probably means more forces" need to be sent there. 

Adm. Mike Mullen's comments put him at odds with a number of lawmakers who are skeptical about any calls for more troops. 

While he was warmly received Tuesday at a confirmation hearing for his second term as chairman of the Joint Chiefs of Staff, there were sharp differences over further increasing a U.S. force in Afghanistan which President Obama nearly doubled this year.  

Senate Armed Services Committee Chairman Carl Levin, D-Mich., warned the United States must "avoid the risks associated with a larger ... footprint." 

Levin said that in a recent visit to Afghanistan, he noticed U.S. Marines outnumbered Afghan security forces five-to-one in Helmand Province. Levin and most others on the committee have called for increasing the size of the Afghan army nearly twice as much as Obama's current strategy envisions. 

Obama is hoping to train an Afghan force of about 134,000 troops by 2010. Levin suggests 250,000 soldiers by 2013, a goal supported by most others on the committee. 

But Arizona Republican Sen. John McCain warned that simply increasing the size of the Afghan army without a corresponding increase in U.S. troops is destined to fail. 

"I've seen that movie before," McCain said, referring to Iraq before the surge. McCain also warned Obama not to be swayed by dwindling public support for the war in Afghanistan. He said there's a "temptation to wash our hands of a difficult situation in Afghanistan. We can't make this fatal mistake again." 

Mullen strongly suggested that the commander of U.S. forces in Afghanistan, Gen. Stanley McChrystal, will recommend more troops be sent to the region in a coming "assessment." 

Mullen expects that will be sent to the White House "in a couple of weeks." Mullen said McChrystal found the situation "much worse than he expected" when he took control of the forces in Afghanistan in June. Mullen said the general was "alarmed by the insurgency" and needs to "retake the initiative from insurgents who have grabbed it over the past three years." 

Mullen said the United States has "very badly under-resourced Afghanistan for the better part of five years." He said it's "very clear we need more resources to execute the president's strategy," though Mullen said he'd await McChrystal's report "to evaluate specifically what that means."

Sen. Jim Webb, D-Va., warned about comparing Afghanistan to Iraq, saying Iraq is "used to a strong central government" and that Afghanistan "has never been governed centrally." Mullen said he favors a "relatively weak central government that isn't corrupt." 

Mullen also touched on the prospect of an Iraqi referendum on the Status of Forces agreement that currently authorizes U.S. troops to be in that country through 2011. He said there is "great concern" by the commander of U.S. forces, Gen. Ray Odierno, and U.S. Ambassador Chris Hill, and that the "outcome is critical." 

Interestingly, Vice President Biden, who made a surprise visit to Iraq Tuesday, said Odierno is "optimistic" and "believes we will be able to meet the letter of the SOFA."

In a speech in March, Obama said our goal is "to disrupt, dismantle and defeat Al Qaeda in Pakistan and Afghanistan, and to prevent their return in the future."