“Carter, the 25th Secretary of Defence and Director of the Belfer Center for Science and International Affairs at Harvard’s Kennedy School, devoted his professional life to national security of the United States and teaching students about international affairs. He was a beloved husband, father, mentor, and friend. His sudden loss will be felt by all who knew him,” the statement on Tuesday read.

Biden in a statement said Carter was born a patriot. “A physicist and national security leader across decades, he served with immense distinction at every level of civilian leadership at the Department of Defense, including as our nation’s 25th Secretary of Defence,” he said.

“Ash was a leader on all the major national security issues of our times – from nuclear deterrence to proliferation prevention to missile defense to emerging technology challenges to the fight against Al Qaida and ISIS. He opened every field of military service to women and protected the rights of transgender service members,” Biden said.