Indian President A.P.J. Abdul Kalam waves at New Delhi's Air Force station on September 11, 2004.
CNN  — 

Former Indian president APJ Abdul Kalam, who was pivotal in the country’s nuclear weapons program, died Monday in northeastern India, his aide H. Sheridan told CNN.

Kalam, 83, was known as the South Asian nation’s “missile man” for his role in developing the country’s defense and nuclear technologies. He collapsed while giving a talk in the city of Shillong, Sheridan said.

From 2002 to 2007, Kalam was the eleventh president of India, serving in that capacity as the supreme commander of the nation’s armed forces. He was the first scientist to hold the office, and was widely viewed as an apolitical figure.

“India mourns the loss of a great scientist, a wonderful President & above all an inspiring individual. RIP Dr. APJ Abdul Kalam,” Indian Prime Minister Modi said on his official Twitter account.

CNN’s Kevin Wang and Ram Ramgopal contributed to this report.