During the early Cold War era, Sweden combined its policy of non-alignment and a low profile in international affairs with a security policy based on strong national defence. The function of the Swedish military was to deter attack. At the same time, the country maintained relatively close informal connections with the Western bloc, especially in the realm of intelligence exchange. In 1952, a Swedish DC-3 was shot down over the Baltic Sea by a Soviet MiG-15 jet fighter. Later investigations revealed that the plane was actually gathering information for NATO. Another plane, a Catalina search and rescue plane, was sent out a few days later and shot down by the Soviets as well. Prime Minister Olof Palme made an official visit to Cuba during the 1970s, during which he denounced Fulgencio Batista's government and praised contemporary Cuban and Cambodian revolutionaries in a speech.