Women will be allowed to hold any job in the United States military — including those in combat units — following a historic announcement by Defense Secretary Ash Carter on Thursday.

Carter said at a news conference that for the first time ever, women in the U.S. military will be allowed to do jobs from which they were previously barred, given they meet specific standards.

“They’ll be allowed to drive tanks, fire mortars and lead infantry soldiers into combat,” Carter reportedly said, according to a recap posted on the Department of Defense’s official website. “They’ll be able to serve as Army Rangers and Green Berets, Navy SEALs, Marine Corps infantry, Air Force parajumpers and everything else that was previously open only to men.”

The jobs will formally become available to women next month, according to the Department of Defense posting, though Carter acknowledged that it will take some time for full integration.

Carter said at the news conference that leaders from all branches of the military had spent the past three years studying the assimilation of women into the previously men-only positions, according to the Department of Defense. Leaders from the Army, Navy, Air Force, and Special Operations Command didn’t indicate that women should be barred from any job.

While the Marine Corps reportedly asked that certain jobs be kept men-only, like machine gunner and fire support reconnaissance, the Department of Defense quoted Carter as saying “we are a joint force and I have decided to make a decision which applies to the entire force.”

The news wasn’t immediately welcomed by everyone.

Sen. John McCain (R-Arizona) and Rep. Mac Thornberry (R-Texas), the chairmen of the Armed Services Committees in their respective legislative houses, released a joint statement in which they said Carter’s decision “will have a consequential impact on our servicemembers and our military’s warfighting capabilities.” They said they want time to review the materials that played into Carter’s decision, including a 1,000-page report from the Marine Integrated Task Force.

One of the findings of that report, according to a September 2015 news release, was that all-male units generally outperformed integrated units in tests designed to simulate combat situations.

“We expect the Department to send over its implementation plans as quickly as possible to ensure our Committees have all the information necessary to conduct proper and rigorous oversight,” McCain and Thornberry said in the statement, adding that they also wanted to see the department’s stance on if changes to the Selective Service Act might now be required.