The Finno–Soviet Agreement of Friendship, Cooperation, and Mutual Assistance, also known as the YYA Treaty from the Finnish Ystävyys-, yhteistyö- ja avunantosopimus (YYA-sopimus) (Swedish: Vänskaps-, samarbets- och biståndsavtalet (VSB-avtalet)), was in effect from 1948 to 1992. The Soviets sought to deter Western or Allied Powers from attacking Russia through Finnish territory, and The Finnish sought to increase Finland's political independence from the Soviet Union. It thus ensured Finland's survival as a capitalist democracy in close proximity to vital communist Russian regions, such as the Kola Peninsula and the old capital Saint Petersburg.

Under the pact, Finland was obliged to resist armed attacks by "Germany or its allies" (in reality interpreted as the United States and allies) against Finland, or against the Soviet Union through Finland. If necessary, Finland was to ask for Soviet military aid to do so. The agreement also recognized Finland's desire to remain outside great-power conflicts, allowing the country to adopt a policy of neutrality in the Cold War.

Due to the uncertain status of the Finno–Soviet relations in the years after the Continuation War, and the precise interpretation of the treaty's wordings, Finland followed the Warsaw Pact countries' decision and did not participate in the Marshall Plan. As a result, Finland's post-war period of economic hardship was prolonged, compared to other European capitalist countries, and it thus became considerably more economically dependent on the Soviet Union. In general, Finland kept its relations towards western military powers very cool (including the proposed Scandinavian Defense Union) and NATO in particular. By avoiding supporting the West, it attempted to fend off Soviet pressure for affiliation with the Warsaw Pact.

The YYA Treaty was a cornerstone in Paasikivi–Mannerheim's foreign policy. It was also a central policy under the presidency of Kekkonen (1956–1981), who dubbed his foreign policy doctrine the Paasikivi-Kekkonen line.

Soviet Union had similar agreements with many nations, that were not directly allied with it like North Korea since 1961 and Vietnam since 1978.

External links

• Agreement of Friendship, Cooperation, and Mutual Assistance at www.mannerheim.fi
• The Paasikivi Policy and Foreign-Policy Thinking at the Paasikivi Society
• The Cold War and the Treaty of 1948 from Library of Congress (the Country Studies)