Since World War II, conceptions of security in the Northern Europe have focused on what has been referred to as the Nordic balance, or Nordic stability — i.e., the notion of a particular pattern or system of security resulting from a combination of alliance membership, armed neutrality, and bilateral arrangements. The components of this multilayered buffer system have been three NATO members — Denmark, Iceland, and Norway — a strongly armed and quasi-permanently neutral Sweden, and Finland. Finland pursues a neutral foreign policy while maintaining since 1948 a bilateral agreement with the Soviet Union — the Treaty of Friendship, Cooperation, and Mutual Assistance (FCMA). The Nordic pattern has thus combined the presence of both East and West in the region through treaty arrangements with a local "backbone," "not-aligned" and armed Sweden.