Gen. James Amos made the remarks to reporters at a defense conference in San Diego hosted by the U.S. Naval Institute and the defense trade group AFCEA.
Amos says most Marines support the Defense Department's lifting of the ban last week, which opened thousands of positions to women.
He pointed out that over the past decade, many male service members already have been fighting alongside women in Iraq and Afghanistan.
Women who serve in supply troops, as clerks and with military police have ended up on the unmarked front lines of modern warfare, blurring the distinction between combat and noncombat jobs. More than 150 women have been killed in wars in Iraq and Afghanistan while serving in support roles.
Many of the positions opened by Defense Secretary Leon Panetta's announcement are in Army and Marine infantry units and in potentially elite commando jobs. It will be up to the military service chiefs to recommend and defend whether women should be excluded from any of those more demanding and deadly positions, such as Navy commandos or the Army's Delta Force.
The infantry units are smaller and spend more grueling time in battle.
"I think from the infantry side of the house, you know they're more skeptical," Amos said. "It's been an all-male organization throughout the history of the U.S. Marine Corps so I don't think that should be any surprise."
Military officials say they will not lower standards, but they are reviewing them to ensure they are necessary in making a warfighter and not just difficult to be difficult.
When asked by The Associated Press about whether women will be allowed to someday serve as SEALs, Chief of Naval Operations Adm. Jonathan Greenert said it will be up to special operations commands to determine how they will transition the standards to females.
"It is a matter of what are the expectations, and is it feasible to change the standards they have right now, physical standards," Greenert said. "They would say early on 'No, we can't do that,' but I think that's really to be determined."
Amos said his branch also wants to gauge how much interest there is among women to join the infantry units and whether enough can qualify for those units. If there is little interest or few can pass the infantry officers school, then certain positions may be closed to women.
Still, he emphasized, that doesn't mean he is expecting that to happen. He said military leaders want to ensure the military continues to be an effective war-fighting force. And if the data and analysis support closing some positions, he believes the defense secretary will support that.
"I have every expectation that the secretary of defense will honor that," Amos said. "It's a commonsense approach to this thing."
The Marine Corps opened its tough infantry course at Quantico, Va., to female volunteers last fall. Two tried unsuccessfully in the first session. In the second session, none signed up. Amos said two female lieutenants have signed up for the third session that will start in March.
Amos said he met with them Monday.
"They're stalwart," he said. "It looks like they're in great shape and they're excited about it."
Amos said he also met with one of the female officers who almost made it to the second-week mark of the course last fall. He said she was forced to drop out because of a stress fracture that was so severe it could have left her permanently injured.
"She did anything but quit," Amos said, adding that the woman was cheered on by her male counterparts. "She's a phenomenal officer."
The woman is now in flight training school in Pensacola, Fla. Amos said she was part of the team so he is optimistic that "we're going about it the right way."
"It's just a very, very difficult course, and it's a very small community," he added.
Women make up about 7 percent of the Marine Corps, compared with about 14 percent overall among the military's 1.4 million active military personnel.
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