and now started the process to end discrimination against women. Otherwise, his tenure has been dominated by budget wrangling, the end of the Iraq war and the troop reduction in Afghanistan.
President Barack Obama has nominated former Republican Senator Chuck Hagel as Panetta's successor.
The decision comes nearly a year after the Pentagon unveiled a policy that opened 14,000 new jobs to women but still prohibited them from serving in infantry, armor and special operations units whose main function was to engage in front-line combat.
Asked last year why women who had served in Iraq and Afghanistan conducting security details and house-to-house searches were still being formally barred from combat positions, Pentagon officials said the services wanted to see how they performed in the new positions before opening up further.
Nearly 300,000 women have been deployed in the US forces in the Iraq and Afghanistan wars over the past 11 years, or about 12 percent of the total. Women have counted some 84 hostile casualties in those wars.
Ending US combat ban will even career playing field, servicewomen say
(Reuters) A Pentagon decision to lift a ban on women in front-line combat roles will remove an obstacle that stymied women's careers but had little meaning on modern battlefields with no clear front lines, U.S. military women said on Wednesday.
Defense Secretary Leon Panetta is expected to formally announce on Thursday that he will lift the policy that excluded women from units whose main job is to engage in combat, U.S. defense officials said.
"Everyone serving in Iraq and Afghanistan is in combat by the very nature of those conflicts," said Peggy Reiber, who retired from the Marine Corps 16 years ago as a first sergeant and lives in a San Diego suburb.
"Women have certainly fought equally and died equally, it's time we were recognized equally."
The move, which could open thousands of fighting jobs to female service members for the first time, knocks down another societal barrier in the US armed forces after the Pentagon in 2011 scrapped its "Don't Ask, Don't Tell" ban on gays and lesbians serving openly in the military.
"I feel like it's beyond time," said Staff Sergeant Tiffany Evans, a soldier stationed at Fort Hood, Texas, describing the move as an overdue recognition that women already serve in combat.
But not all were pleased by the decision. The conservative Concerned Women for America Legislative Action Committee complained the move could detract from the military's role