well lets see, if its not already self explanatory then its the act against aggression
Joseph Stalin
Joseph Stalin and Benito Mussolini
Germany
The Soviet Union (Which is now Russia).
Joseph Stalin and the Soviet Union.
In August 1939.
Nazi-Soviet nonagression pact.
The Molotov-Ribbentrop Pact was signed 23 August 1939.
The Soviet Union signed a non-agression pact to buy time before the Germans attacked them. The pact also included secret clauses, one of which planned the division of Poland.
Soviet foreign minister Maxim Litvinov was replaced by Vyacheslav Molotov in 1939. Molotov negotiated the German-Russian Nonagression pact in August of 1939.
In 1934 - five years before the start of the World War 2 - Germany and Poland signed a non-agression pact. I wonder if that is what you have in mind.
There has probably been more than one non-aggression pact in history but the most famous is the 1939 pact between Nazi Germany and the Soviet Union - which Germany broke in 1940.