US Defense Secretary Leon Panetta has decided to lift a ban on women serving in combat, a senior defense official said Wednesday, after a decade of war that saw female troops thrust onto the battlefield. Panetta and General Martin Dempsey, the chairman of the US Joint Chiefs of Staff, \"are expected to announce the lifting of the direct combat exclusion rule for women in the military,\" the official, who spoke on condition of anonymity, told reporters. \"This policy change will initiate a process whereby the services will develop plans to implement this decision, which was made by the Secretary of Defense upon the recommendation of the Joint Chiefs of Staff,\" the official said in an email. The official announcement of the move, which would open up hundreds of thousands of combat posts to women, was expected on Thursday, officials said. In February last year, Panetta removed a ban on women for about 14,000 combat-related jobs in an incremental move that was criticized as timid by some activists. Calls to lift the blanket prohibition have mounted after more than ten years of war in which women fought and died in counter-insurgency campaigns in Iraq and Afghanistan where front lines were blurred. Some senior officers have privately voiced concerns that infantry and special forces units require major upper body strength and that difficult physical tests should not be relaxed for female recruits. But female veterans and activists say they are only demanding an equal chance to apply for combat jobs -- and not any special treatment. US commanders began taking a second look at the ban in 2010 to reflect the reality on the battlefield, as the wars in Iraq and Afghanistan have put women in harm\'s way in any case. Panetta\'s decision would apply mainly to the Army and the Marine Corps, as the Air Force and Navy already have lifted most prohibitions on women in combat, with women flying warplanes and launching weapons on ships. In 2010, the Navy opted to allow women to serve on submarines. Women make up about 14.5 percent of the active duty US military, or about 204,000 service members, according to the Pentagon. The American Civil Liberties Union praised the move. \"We are thrilled to hear Secretary Panetta\'s announcement today recognizing that qualified women will have the same chance to distinguish themselves in combat as their brothers-in-arms, which they actually already have been doing with valor and distinction,\" Ariela Migdal, senior staff attorney with the ACLU Women\'s Rights Project, said in statement. \"But we welcome this statement with cautious optimism, as we hope that it will be implemented fairly and quickly so that servicewomen can receive the same recognition for their service as their male counterparts.\"