The division between which two countries was referred to as the 'Iron Curtain'?

The division between which two countries was referred to as the 'Iron Curtain'?

Explanation

 The term "Iron Curtain" primarily referred to the division between West Germany and East Germany

During the Cold War, the Iron Curtain was a political metaphor

Used to describe the political and physical boundary dividing Europe into two separate areas from the end of World War II in 1945 until the end of the Cold War in 1991