In 2011, during the performance at the Yaroslavl Global Policy Forum, President Medvedev has declared that the doctrine of Karl Marx on class struggle is extremist and dangerous. Progressive economic stratification which can be less evident in period of economic growth, leads to acute conflicts between rich and poor people in period of downturn. In such conditions, the doctrine on class struggle is being revived in many regions of the world, riots and terrorist attacks become reality, by opinion of Medvedev.