Marine Corps senior leaders have begun to express cautious openness to the idea of making the service's boot camps fully co-ed. But if Congress has its way, the service may be pushed toward full integration sooner than expected.

The final conference version of the 2020 National Defense Authorization Act includes a provision that would require the service to integrate both its East Coast and West Coast entry-level training facilities within the next eight years.

According to the provision, the Corps would be required to end any segregation based on gender at Marine Corps Recruit Depot Parris Island, South Carolina, within five years of the bill's enactment. At Marine Corps Recruit Depot San Diego, which has never trained female recruits, the service would have eight years to reach full integration.

The provision was introduced earlier this year by Rep. Jackie Speier, D-California, a vocal proponent of women in the service. It survived the committee conference process and now faces a vote in the House and Senate; passage is expected.

The Marine Corps is the only military service that still separates recruits by gender during parts of the training process. Historically, service leaders have said this practice eliminates distraction and facilitates stronger bonding and mentorship roles in the early phases of boot camp.

But the head of Marine Corps Training and Education Command, Maj. Gen. William Mullen, told Military.com in a November interview that he was open to the idea of ending gender segregation, if the data supported it.

Mullen has called for a Marine Corps-commissioned academic study on a gender-integrated boot camp model to gather findings on the potential impacts of such a change before making a decision.

In March, the Marine Corps graduated its first co-ed company at Parris Island in a limited experiment. Platoons within the company were still divided by gender. Mullen said in the interview that study will continue, with as many as eight co-ed companies graduating from Parris Island over the next year.

"We think we have it right ... but how much of that is our own biases?" Mullen said. "How much of that is a 'we invented it here' kind of thing?"

-- Gina Harkins contributed to this report.

-- Hope Hodge Seck can be reached at hope.seck@military.com. Follow her on Twitter at @HopeSeck.