The review includes researching the experiences of Australia, Canada, and other nations with whom American troops have worked closely in Iraq and Afghanistan, according to a senior Pentagon official. Some countries have had "three to ten years to go through this process, to integrate women" into combat roles, the official said.

There are roughly a dozen nations that have opened "close combat roles" to women. Those roles are defined by a 2010 British Ministry of Defense (MOD) study as those that include "engaging an enemy on the ground ... while being exposed to hostile fire and a high probability of physical contact with the hostile forces personnel."

In many parts of the world, these efforts have moved quickly once they've begun. Though