 While chairman of the AEC , Seaborg participated on the negotiating team for the Limited Test Ban Treaty ( <unk> ) , in which the US , UK , and USSR agreed to ban all above @-@ ground test detonations of nuclear weapons . Seaborg considered his contributions to the achievement of the <unk> as one of his greatest accomplishments . Despite strict rules from the Soviets about photography at the signing ceremony , Seaborg sneaked a tiny camera past the Soviet guards to take a close @-@ up photograph of Soviet Premier Nikita Khrushchev as he signed the treaty . 
