A former chairman of the Joint Chiefs of Staff, secretary of state and national security adviser, Mr. Powell died of complications of Covid-19, his family said.

Colin L. Powell, who in four decades of public life served as the nation’s top soldier, diplomat and national security adviser, and whose speech at the United Nations in 2003 helped pave the way for the United States to go to war in Iraq, died on Monday. He was 84.

The cause was complications of Covid-19, his family said in a statement, adding that he had been vaccinated and was being treated at Walter Reed National Military Medical Center, in Bethesda, Md., when he died there.