Updated 6:10 p.m.: Defense Secretary Leon Panetta will lift the military's ban on women serving in combat, according to press reports that cite an unnamed senior adviser.
The historic decision will open about 230,000 positions (many in Army and Marine infantry units), to women, according to the AP.
Allowing women to serve in small, front-line combat units overturns a 1994 policy preventing the service of women in some of the military's most dangerous deployments.
The source said that while some jobs will open to women this year, others in elite commando units, such as the Navy SEALs and Army's Delta Force, may take longer to integrate.
Many female service members have long complained that combat prohibitions have prevented them from being seen as equals in the military and impeded their careers, as combat experience is seen as an important qualification for top officers.
Military service chiefs must submit initial implementation plans to Panetta by May 15 and will have until January 2016 to seek special exceptions for positions they believe should remain male only, said the AP.
Women now comprise about 14% of the 1.4 million active military personnel.