Answer :
Communist treaty between Central & Eastern European countries during the cold war, it had a similar format of NATO
The Warsaw Pact, 1955, was a defense agreement, which allowed the Soviets to have control of the military of at least seven European countries. The pact was signed in Warsaw, Poland. The seven countries that were part of the pact were: Poland, Romania, Hungary, East Germany, Czechoslovakia, Bulgaria, and Albania (I believe). If any of these countries were attacked by outside forces the other' in the pact would come to that country's aid. The one thing these seven nations had in common was that they were Communist at that time. In 1991 the Warsaw Pact collapsed.
It is through this Warsaw Pact that the USA would also decide to form a coalition/organization known as NATO (North Atlantic Treaty Organization). The nations at that time who were part of NATO were non-communist countries and didn't support communist governments.
Hopefully this helped and good luck.