Women will eventually have to register for the draft if "true and pure equality" is to be realized in the U.S. military, Army Secretary John McHugh said Monday.

"If your objective is true and pure equality then you have to look at all aspects" of the roles of women in the military, McHugh said, and registration for the draft "will be one of those things. That will have to be considered."

McHugh said draft registration was not a subject to be decided by the services or the Department of Defense, and will ultimately have to be dealt with by Congress. He expected a "pretty emotional debate and discussion."

However, as more military occupational specialties are opened to women, the debate on Selective Service System registration was inevitable, McHugh said. "If we find ourselves as a military writ large where men and women have equal opportunity, as I believe we should," he said.

The question on women and the draft was posed to McHugh and Gen. Mark Milley, the new Army chief of staff, at the annual three-day meeting and exposition of the Association of the U.S. Army at the Walter E. Washington convention center in Washington, D.C. Milley deferred the question to McHugh, saying he could not comment on policy.

The subject of women registering for the draft was a topic of debate at an Aspen National Security forum in Colorado this summer.

In one panel discussion, retired Navy Adm. Eric Olson, former commander of the SEALs and the Special Operations Command, said that women should have to register for the draft if they also can serve in combat.

On a separate panel, Air Force Secretary Deborah James said that she would have no problem with women registering for the draft.

Defense Secretary Ashton Carter was to decide in January on whether combat roles, mostly in the infantry, armor, artillery and Special Operations, should be opened to women.

Proposals to abolish the Selective Service System as a relic of the era before the all-volunteer force of the early 1970s occasionally come before Congress, but the proposals have never gained traction.

Nearly 17 million male U.S. citizens and male immigrant non-citizens between the ages of 18 and 25 currently are registered for conscription with the Selective Service System, an independent government agency.

The 18-25 males are required by law to have registered within 30 days of their 18th birthdays and must notify Selective Service within 10 days of any changes to information they provided on their registration cards, such as a change of address. Violations can be considered felonies.

--Richard Sisk can be reached at Richard.Sisk@military.com.