As a deadline nears for the Pentagon to decide whether to fully integrate women in U.S. combat operations, associations are making a case for why women are fit for battle in response to a Marine Corps study that delivers a mixed assessment on the subject.

According to a Marine Corps report leaked last week, test studies of mixed-gender combat groups showed no harm was done to morale, a longtime concern among critics. Indeed, according to the report, the men and women in the test group “feel a strong sense of belonging to the military, even more so when compared to other Marines of the operating forces.”

There has been this band of brothers idea that there is something special about having only men.

But the Marine Corps also found that women suffered more injuries than men and that all-male combat groups performed better. And according to the Washington Post, seven cases of sexual assault were reported in the unit assembled to study mixed-gender combat.

The study was prompted by a Defense Department decision in 2013 that a rule excluding women from combat roles be repealed on January 1, 2016, unless the Pentagon can justify exemptions.

The source of the leaked report is Women in International Security, a membership organization that includes diplomats, scholars, and members of the military. WIIS has been monitoring integration issues and advocating for more women in combat, and is challenging the Marines’ findings about women’s combat readiness.

“There has been this band of brothers idea that there is something special about having only men, and adding women will ruin it,” WIIS senior fellow Ellen Haring told The New York Times. “The study doesn’t bear that out.”

WIIS is joined in its critique by Service Women’s Action Network, an advocacy group challenging discrimination and sexual violence in the military. SWAN CEO Judy Patterson dismissed the report, telling the Los Angeles Times that it is a “skewed attempt to set the stage for the Corps to request exceptions to the Department of Defense’s mandate for full combat integration.”

To date, no such exemptions have been formally requested by any branch of the U.S. military, though the Marines reportedly asked Navy Secretary Ray Mabus to keep some units male only.

(MCRD Parris Island, S.C./Flickr)