The Cold War was a state of political and military tension in the period
following World War II (WWII), from 1947 to 1991,
between the Western Block and the Eastern Block.
The Western Block consisted of the United States (US), Europe and
NATO, whilst the Eastern Block consisted of the Soviet Union (USSR)
and its Warsaw Pact allies. The ideological and physical border between
the two blocks was known as the Iron Curtain.
During the Cold War, both sides used
spy radio sets for clandestine operations,
espionage, stay-behind organisations (SBO) and
one-way voice links.