As Yuri Andropov became the new General Secretary of the Communist Party of the Soviet Union, Sagdeev participated in the work of a think tank with Gorbachev as the head, which was mandated to find scientific justifications for the nuclear disarmament. Later, as Gorbachev became the new General Secretary of the Communist Party of the Soviet Union, following Ronald Reagan's Strategic Defense Initiative (SDI), they advised the Soviet leadership not to worry and not to respond by creating a similar program.