In case of what country's attack was the origins of the Central Powers?
Dual Alliance (1879) The Dual Alliance was a defensive alliance between Germany and Austria-Hungary, which was created by treaty on 7 October 1879 as part of Bismarck's system of alliances to prevent or limit war. The two powers promised each other support in case of attack by Russia. Also, each state promised benevolent neutrality to the other if one of them was attacked by another European power (generally taken to be France, even more so after the Franco-Russian Alliance of 1894). Germany’s Otto von Bismarck saw the alliance as a way to prevent the isolation of Germany and to preserve peace, as Russia would not wage war against both empires.
Operation Poro Operation Poro (the Finnish for Reindeer), was a planned invasion of the north Scandinavian peninsula by the Soviets. The plan originated in 1932 and was rehashed during the period 1935 to 1936. The plan was for a Soviet offensive through northern Finland and Sweden with the aim of occupying northern Norway. The Norwegian Labour Party was involved in similar efforts already from the early 1920s to the early 1930s, as exposed in a parliamentary report in 1932.