1917 saw the fall of the Tsarist regime in Russia, producing a republic under Alexander Kerensky. The October Revolution shortly followed, which empowered the Bolsheviks to seize control of much of Russia. The ensuing Red Terror generated fear among Americans, who had come out of the First World War with several new security laws such as the Espionage Act in 1917, the Sedition Act of 1918, and the Immigration Act of 1918. This legislation enabled the American government to investigate and prosecute anarchists in response to terrorist attacks. Bombings by Galleanist anarchists in the spring of 1919 contributed to a public hysteria about the communist threat, now called the First Red Scare.