In 1936, both Bulgaria and Mexico signed a "Treaty of Friendship". Diplomatic relations between both nations were formerly established on 6 January 1938. In 1941, during World War II, both nations suspended diplomatic relations when Bulgaria joined the Tripartite Pact (a military alliance between the Axis powers and Bulgaria, among others). In May 1942, Mexico declared war on the Axis powers. Diplomatic relations between both nations were resumed on 11 July 1974. In 1976, both nations opened resident embassies in each other's capitals.