The Tripartite Pact, also known as the Berlin Pact, was an agreement between signed on September 27th, 1940 between Germany, Italy and Japan by German Minister of Foreign Affairs Joachim von Ribbentrop (1893-1946), Italian Minister of Foreign Affairs Gian Galeazzo Ciano (1903-1944) and Japanese Ambassador to Germany Saburō Kurusu (1886-1954).
The defensive military alliance was later joined by Hungary, Romania and Slovakia on November 20th, 23rd and 24th, 1940. Bulgaria and Yugoslavia did the same on March 1st and March 25th, 1941.
In the latter case, it provoked a coup d’état in Belgrade on March 27th, which led to an invasion by Germany, Italy and Hungary on April 6th. As a result, the former Yugoslav republic of Croatia gained independence and acceded on June 15th 1941.
As Germany and Japan had already been allied since the signing of the Anti-Comintern Pact on November 25th, 1936, the Molotov–Ribbentrop Pact of August 23rd, 1939 between Germany and the Soviet Union came as a surprise to Japan.
Especially, as at the time it was engaged against the Soviets in the Battles of Khalkhin Gol in Mongolia, which ended in September of that year in defeat for Nippon.
The Soviet–Japanese Neutrality or Japanese–Soviet Nonaggression Pact was inked on April 13th, 1941 in Moscow. In consequence, Tokyo refused German calls to intervene in Operation Barbarossa, which began on June 22nd, 1941.
In the document, Japan, Germany, and Italy considered it as the condition of any lasting peace that all nations in the world be given each its own proper place.
Therefore, they decided to cooperate with one another in their efforts in the regions of Europe and Greater East Asia, respectively. Their prime purpose was to establish and maintain a new order of things, calculated to promote the mutual prosperity and welfare of the peoples concerned.
The three governments expressed their desire to extend cooperation to nations in other spheres of the world that were inclined to direct their efforts along lines similar to their own.
They would assist one another with all political, economic and military means if one of the Contracting Powers was to be attacked by a Power at that time not involved in the European War or in the Japanese-Chinese conflict.
Such wording notably excluded those who had invaded Poland on September 17th, 1939. The three Contracting Powers explicitly affirmed that the agreement in no way affected the political status between them and Soviet Russia.
Directed primarily at the Unites States, the Pact´s practical effects were nevertheless limited since the Italo-German and Japanese operational theaters were on opposite sides of the world and the three countries had disparate strategic interests.
It was however invoked following the Japanese attack on Pearl Harbor on December 7th, 1941, as the US declared war on Japan the next day. Germany and Italy fulfilled their obligations on December 11th. World War II had definitely become a global conflict.