The start of the construction of an oil export pipeline from Eastern Siberia to the Pacific Ocean marks an important new phase in Russia's policy of diversifying its exports away from Europe. Sales to the former Comecon nations of Eastern Europe have been eroded over the last decade-and-a-half since the countries there have tried to import crude oil from the North Sea and elsewhere, following the collapse of the Soviet economic bloc with its barter system of trade in oil and major commodities. Recently, Western Europeans have expressed concerns about the share of Russian supplies in their energy balances, particularly since the argument between Russia and Ukraine over gas supplies at the beginning of 2006 (see 'Gas and Power', February 2006). Since then, the European Commission has been warning of the danger of the European Union's becoming over-reliant on Russian energy.