 Complete the following phrase:  The Russo-Persian Treaty of Friendship was signed on 26 February 1921 in Moscow between representatives of Persia and Soviet Russia. Based on the terms of the treaty, all previous agreements made between the signatories including the Treaty of Turkmenchay were canceled. Moreover, both Russia and Iran were given full and equal shipping rights in the Caspian Sea along with the right to fly their respective national flags on their commercial vessels. Ratifications were exchanged in Teheran on 26 February 1922. It was registered in League of Nations Treaty Series on 7 June 1922. The original purpose of the treaty was to prevent White Russian counter-revolutionary forces who fled to Iran after the Bolshevik Revolution from attacking the Soviets from Iranian territory as had happened as late as 1918. The passage of the treaty, and particularly articles 5 and 6, was subject to vigorous debate in the Persian parliament; anti-British sentiment, however, lead to its acceptance without alteration. The treaty would serve as the basis for a Soviet occupation in 1941, and articles 5 and 6 were eventually repudiated by Iran in 