The US military on Thursday will ease some restrictions on women in combat, opening up thousands of jobs that had been off-limits to female soldiers, defense officials said. The move marks a milestone for the American military, which has lifted prohibitions on women's roles since the 1970s in incremental steps. "The department plans tomorrow to open 14,000 jobs that previously had been closed to women in the military," a senior defense official told AFP. The official, who spoke on condition of anonymity, described the change as a first step and that in time, more positions were likely to be available to women. "This is only the start," the official said. "It's conceivable in the future, after conducting more reviews, that more jobs will be open to women," he said. The changes mainly apply to the Army, as well as the US Marine Corps, the official said. The Air Force and Navy have few remaining restrictions on female service members, after a 2010 decision that opened the door to women serving on submarines. Until now, female intelligence officers, signal officers and or those with other specialties could not serve in battalions likely to face direct combat. The new policy will change that prohibition and allow women "more tactical opportunities" instead of being confined to brigade-level posts, the official said. Defense Secretary Leon Panetta approved the policy change after receiving an internal report that looked at women' roles and the experience of a decade of war that thrust women into battle. Despite rules designed to keep women away from units engaged in ground combat, women have found themselves in firefights in Iraq and Afghanistan where there were no clearly defined front lines in counter-insurgency campaigns. Officials described the new rules as more of an evolutionary step and not a radical reform, revising policies that were out of touch with realities on the battlefield. The Pentagon is due to formally inform Congress of the change on Thursday, giving lawmakers a brief period to delay or block the measure before it takes effect. Congress ordered a review of women's roles after an advisory panel recommended rescinding all remaining restrictions that have prevented women from serving in infantry and other ground combat units.