Ash Carter, who as defense secretary in the final two years of the Obama administration opened military combat jobs to women and ended a ban on transgender people serving in the military, has died at age 68.

Carter died after suffering a heart attack on Monday evening, according a statement Tuesday from Douglas Elmendorf, dean of Harvard University’s Kennedy School. Carter had served as director of the school’s Belfer Center for Science and International Affairs.

Before Carter was named the Defense Department secretary, he served in President Barack Obama’s administration as its top procurement officer and oversaw the department’s effort to speed more than 24,000 Mine Resistant Ambush Protected vehicles to Iraq and Afghanistan. At the time, thousands of U.S. troops were being maimed or killed by roadside bombs because there was not adequate protection in the vehicles they were operating. Carter frequently mentioned the rapid development and procurement of those vehicles as one of his proudest accomplishments.

“At peak production, the United States shipped over 1,000 MRAPs a month to theater. And there, they saved lives,” Carter said at a 2012 ceremony marking the completion of the vehicle production. “And you all know me, I would have driven one in here today, if I could get it through the door.”

In December 2015, after three years of study and debate, Carter ordered the military to open all jobs to women, removing the final barriers that kept women from serving in combat, including the most dangerous and grueling commando posts.

The following year, Carter ended the ban on transgender troops serving in the U.S. military, saying it was the right thing to do.

“Americans who want to serve and can meet our standards should be afforded the opportunity to compete to do so,” Carter said in June 2016, laying out a one-year plan to implement the change. “Our mission is to defend this country, and we don’t want barriers unrelated to a person’s qualification to serve preventing us from recruiting or retaining the soldier, sailor, airman, or Marine who can best accomplish the mission.”

Carter, a Philadelphia native, served at the 25th defense secretary and “loved nothing more than spending time with the troops, making frequent trips to Iraq and Afghanistan to visit U.S. forces with his wife Stephanie,” his family said in a statement. “Carter always set politics aside; he served presidents of both parties over five administrations.”

(AP)