In his 36 years representing Indiana in the U.S. Senate, Richard Lugar became one of the most influential Republican voices on foreign policy and, specifically, nuclear nonproliferation. Lugar, who passed away on Sunday, made limits on nuclear arms a key part of his work both in the Senate and later through the Lugar Center. Today, that legacy is as important as ever and one that lawmakers must carry on.

Lugar’s best-known work was the Soviet Threat Reduction Act, passed in 1991 and co-sponsored by Sen. Sam Nunn, D-Ga. That legislation created the Cooperative Threat Reduction program, providing U.S. funds to deactivate nuclear warheads in the former Soviet Union.