The article examines the foreign policy positions of Moscow and Washington in the context of the events in Western Sahara in the second half of the 1970s, taking into account the diplomatic activities of the Communist parties of Italy (Partito Comunista Italiano, PCI), France (Parti communiste français, PCF) and Spain (Partido Comunista de Españа, PCE). The research is based on the published documents of the US president J. Carter's administration, sources of the US State Department and the Central Intelligence Agency, as well as unpublished declassified documents of the CPSU Central Committee from the funds of the Russian State Archive of Contemporary History, and also press materials and memoirs. It is argued that 1) the conflict in Western Sahara united the PCI, the PCF and the PCE in a campaign of solidarity with the Polisario Front against the background of Moscow's non-recognition of the Sahrawi Arab Democratic Republic (SADR) and Washington's supply of arms to Morocco to suppress the struggle for Western Saharan independence; 2) The United States perceived the activity of the Western European Communist Parties in organizing solidarity campaigns with the Polisario Front as a minor episode of international politics that did not lead to recognition of SADR independence by Western European countries; 3) U.S. diplomats observed the speeches of Western European Communist Parties in support of the Polisario, but did not bring their analysis to practical recommendations that would have adjusted tactics toward these Communist Parties. The Eurocommunists' support for the Polisario wasn't coordinated with Moscow.