Tripartite Pact
The Tripartite Pact, also known as the Berlin Pact, was an agreement between Germany, Italy, and Japan signed in Berlin on 27 September 1940 by, respectively, Joachim von Ribbentrop, Galeazzo Ciano, and Saburō Kurusu (in that order) and in the presence of Adolf Hitler.[1] It was a defensive military alliance that was eventually joined by Hungary (20 November 1940), Romania (23 November 1940), Slovakia (24 November 1940), Bulgaria (1 March 1941), and Yugoslavia (25 March 1941). Yugoslavia's accession provoked a coup d'état in Belgrade two days later. Germany, Italy, and Hungary responded by invading Yugoslavia. The resulting Italo-German client state, known as the Independent State of Croatia, joined the pact on 15 June 1941.
Type
27 September 1940
- Original
Germany
Italy
Japan - Subsequent
Hungary
Romania
Slovak Republic
Bulgaria
Croatia 
Yugoslavia (for two days)
The Tripartite Pact was, together with the Anti-Comintern Pact and the Pact of Steel, one of a number of agreements between Germany, Japan, Italy, and other countries of the Axis Powers governing their relationship.[2]
The Tripartite Pact formally allied the Axis Powers with one another, and it was directed primarily at the United States.[3] Because of the distance difference between Japan and the two European Powers, the pact recognized two different regions that were to be under Axis rule.[4] Japan recognized "the leadership of Germany and Italy in the establishment of a new order in Europe". In return, Germany and Italy recognized Japan's right to establish a new order "in Greater East Asia".[5] But the pact's practical effects were limited since the Italo-German and Japanese operational theatres were on opposite sides of the world, and the high contracting powers had disparate strategic interests. As such, the Axis was only ever a loose alliance.[6] Its defensive clauses were never invoked,[7] and signing the agreement did not oblige its signatories to fight a common war per se.[8]