This dissertation examines the Soviet Union and the Afghan communists’ perception and policies on Islam during the Soviet-Afghan War and their relations with the “Muslim World”. It makes two principal arguments: (a) The Soviet and Afghan communists’ concern with Islam came late into the conflict. Testifying to an ideological approach to reforming the country, the first phase of the war only saw Babrak Karmal, the ruler installed by Moscow, try to instrumentalise Islam in support of his regime while retaining a Marxist-Leninist platform. By the same token, the Soviets failed to give Islam its due importance. This disregard toward religion rendered even the limited prospects of gaining support for Karmal’s regime moot. This approach to Islam only changed after the Soviets replaced Karmal with Mohammad Najibullah and prepared to withdraw, admitting that their strategy of building socialism in Afghanistan had failed. (b) Only late into the war did the Soviet Union started seriously paying attention to an Islamist threat to Central Asia from Afghanistan. While concerns related to Islamism were present at the moment of the intervention, these were largely circumscribed to the KGB. In the Kremlin, the threat of Islamism registered in 1987 as the Mujahideen conducted attacks inside the USSR and tensions surfaced in Central Asia. It was however never fully conceptualised by Soviet elites who continued to see it as mostly a tool to be instrumentalised by the US, Iran, or Pakistan. The Soviets believed that the Islamists had little agency on their own and that their ideology could not find massive appeal among Soviet Muslims.