The Navy also announced that it is opening jobs for female sailors on smaller attack submarines — ships that had traditionally been closed to women largely due to privacy concerns in extremely close quarters.
There long has been opposition to putting women in combat, based on questions of whether they have the necessary strength and stamina for certain jobs, or whether their presence might hurt unit cohesion. But the Pentagon's announcement was largely hailed by lawmakers and military groups. There were only a few offering dissenting views.
Spc. Jean Sardonas, who works as a lab technician at a hospital at Fort Bliss in Texas, said she considered joining an Army team that faces combat situations. But since she's had children, she said her perspective had changed.
"If you see the enemy, well, that's the enemy, but now if you see a kid with a gun you're going to think twice" about shooting him, she said.
Sen. Jim Inhofe of Oklahoma, who will be the top Republican on the Senate Armed Services Committee, said he is concerned about the possible impact of completely ending the ban, adding that he suspects legislation may be needed to stop changes that would be detrimental.
Under the new memo, military service chiefs will have until May 15 to develop plans for allowing women to seek the combat positions. Some jobs may open as soon as this year, while assessments for others, such as special operations forces, may take longer.
The services will have until January 2016 to argue that some positions should remain closed to women.
Thursday's move fits into the broad agenda President Barack Obama previewed for his second term during Monday's inaugural address, which focused in particular on issues of equality. It also comes on the heels of a presidential election in which Obama won the majority of female voters following a campaign that focused heavily on women's issues, though not women in combat specifically.
The change also comes as Panetta wraps up his tenure as defense secretary. The order expands the department's action of nearly a year ago to open about 14,500 combat positions to women, nearly all of them in the Army.
Under the 1994 Pentagon policy, women were prohibited from being assigned to ground combat units below the brigade level. A brigade is roughly 3,500 troops split into several battalions of about 800 soldiers each. Historically, brigades were based farther from the front lines, and they often included top command and support staff.
The necessities of combat in Iraq and Afghanistan, however, propelled women into jobs as medics, military police and intelligence officers that were sometimes attached — but not formally assigned — to battalions. So while a woman couldn't be assigned as an infantryman in a battalion going out on patrol, she could fly a helicopter supporting the unit, or move in to provide medical aid if troops were injured.
Dempsey suggested that eliminating the ban on women in some combat roles could help with the ongoing sexual assault and harassment problems in the military.
"When you have one part of the population that is designated as warriors and another part that's designated as something else, I think that disparity begins to establish a psychology that in some cases led to that environment." said Dempsey. "I have to believe, the more we can treat people equally, the more likely they are to treat each other equally."
AP National Security Writer Robert Burns, White House Correspondent Julie Pace and AP Broadcast reporter Sagar Meghani in Washington and AP writer Juan Carlos Llorca in El Paso, Texas, contributed to this report.
Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.