LONDON, Oct 10 (Reuters) – BP Chief Executive Bob Dudley said if the United States imposed sanctions on Russian energy firms Gazprom and Rosneft such as it did on aluminium producer Rusal, it would virtually shut down Europe’s energy systems. BP is the second-biggest shareholder in Rosneft at 19.75 percent. Speaking on Wednesday at an Oil and Money conference in London, Dudley added that BP was planning on a cycle of oil prices at $60-$65 a barrel.