The Arkhangelsk-Astrakhan line or A-A line was the proposed eastern border of the Nazi German empire. Operation Barbarossa, Germany's invasion of the Soviet Union, failed to secure either of the two Russian cities. Adolf Hitler and other Nazi officials believed that the cities of Arkhangelsk in northwestern Russia and Astrakhan in southwestern Russia should mark the frontier between a Greater German Reich and a weakened Soviet Union. Territory east of the Ural Mountains was seen as undesirable. However, the Germans later decided to expand the frontier of their proposed empire to the Urals and send the remaining Slavic populations over the mountains and thus out of Europe. This applied to any Slavs that would not otherwise be recruited for slave labour. With the failure of Operation Barbarossa, this plan was never achieved.