Who began political and economic reforms in the Soviet Union during Ronald Reagan's presidency?

Mikhail Gorbachev began political and economic reforms in the Soviet Union during Ronald Reagan's presidency. He introduced policies known as glasnost (openness) and perestroika (restructuring) in the mid-1980s, aimed at increasing transparency and reforming the economy. These reforms contributed to a significant shift in Soviet society and ultimately played a crucial role in the end of the Cold War.