Former Defense Secretary Ash Carter died Monday evening after a heart attack, according to a family statement. He was 68.

Carter, a native of Philadelphia, served in the top Defense Department role under President Barack Obama from 2015 to 2017. He also served in a variety of other Pentagon leadership roles over five presidential administrations.

In Tuesday’s statement, his family described Carter’s death as a “sudden loss.”

“While he was known for his keen understanding of military technology, nuclear weapons, and international affairs, Secretary Carter 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,” they said.

Carter’s tenure as defense secretary is perhaps most remembered for his order to open to women all military jobs, including combat assignments. The decision came after years of study by military leaders and strong opposition from conservative groups.

Months later, Carter also announced the military would end its ban on transgender troops serving in the ranks. That order was later overturned by President Donald Trump when he took office, and subsequently reversed again after President Joe Biden was elected.

In a statment, Obama called Carter “a keen student of history, a brilliant physicist, and a steadfast defender of our men and women in uniform.”

“As president, I relied on Ash’s strategic counsel as we invested in innovation and a stronger, smarter, more humane, and more effective military for the long term.,” he said. “Under his leadership, America accelerated its counterterrorism efforts, opened combat roles to women, modernized its weapons systems, and strengthened our alliances around the world.”

Carter, who rose from the Pentagon’s acquisition chief to deputy defense secretary, spearheaded innovation efforts and outreach to the commercial tech sector, including establishing the Defense Innovation Unit.

To protect troops from roadside bombs at the height of the wars in Iraq and Afghanistan, he oversaw the rapid development and fielding of mine-resistant ambush protected vehicles, known as MRAPs.

At Carter’s swearing-in ceremony in 2015, he said the Pentagon had to “think outside this five-sided box,” a dig at the Pentagon’s plodding weapons development process. He later launched the department’s “Better Buying Power” initiative, meant to guide the acquisition workforce to smarter and more efficient purchasing.

The high-level organization the Pentagon is using today to rush military aid to Ukraine is based on a bureaucracy-busting model Carter originated to speed supplies to troops in Afghanistan, Iraq and Syria.

The Senior Integration Group-Ukraine copied the Warfighter Senior Integration Group, which Carter launched in the middle of the war on terror to quickly deploy surveillance aerostats, working dogs and bomb-resistant underwear to troops.

“It goes back to Ash Carter,” Ellen Lord, a former undersecretary of defense for acquisition and sustainment and defense executive, told Defense News in a May interview.

Since 2017, Carter had worked as director of the Belfer Center for Science and International Affairs at Harvard’s Kennedy School. Family members said Carter believed “his most profound legacy would be the thousands of students he taught with the hope that they would make the world a better and safer place.”

The Associated Press contributed to this story.

Leo covers Congress, Veterans Affairs and the White House for Military Times. He has covered Washington, D.C. since 2004, focusing on military personnel and veterans policies. His work has earned numerous honors, including a 2009 Polk award, a 2010 National Headliner Award, the IAVA Leadership in Journalism award and the VFW News Media award.

Joe Gould was the senior Pentagon reporter for Defense News, covering the intersection of national security policy, politics and the defense industry. He had previously served as Congress reporter.

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