Explanation:

• Hungary - Hungary became the fourth member of the Tripartite Pact. Hungary played a large role in the invasion of Russia.
• Bulgaria - Bulgaria started out on the Axis side of the war, but after being invaded by Russia ended up on the side of the Allies.
• Romania - Similar to Bulgaria, Romania was on the side of the Axis Powers and helped to invade Russia. However, by the end of the war they changed sides and fought for the Allies.
• Finland - Finland never signed the Tripartite Pact, but fought with the Axis countries against Russia.