Why were the USSR and US at crossroads following the world wars?

The USSR and the US were at crossroads following the world wars for many reasons. From just after the end of World War II until about 1991, this period was known as the Cold War. Neither country wanted to get involved in another physical war. But political ideologies, culture clashes, geopolitical issues, and Russian imperialism led to wars in Korea, Vietnam and Afghanistan.

The Cold War only came to end after Mikhail Gorbachev introduced the policies of glasnost and perestroika. This gave the Russian people a taste of freedom and various revolutions helped to being an end to the Cold War.