Explain the effects of the collapse of the USSR in the period 1985-91 upon the foreign policy of the USA.
The end of the Cold War made the United States have to reorient from being one competitor in the Cold War to being the world's only superpower.
When the Cold War was going on, the US had one primary focus. It had to try to prevent the spread of communism. The US had one adversary and nothing else really mattered. This made foreign policy less complex than it would later become. Everything the US did had to be looked at through the lens of containment.
After the USSR collapsed and the Cold War ended, US foreign policy was much less clear. Was the US to pull back and enjoy a "peace dividend?" Was the US to become the "world's policeman" now that the Soviet Union was not around to prevent the US from doing whatever it wanted in foreign policy? Where would the US now intervene and in what circumstances? These fundamental questions showed that US foreign policy was no longer as clear cut as it had been during the Cold War.