Two incidents that occurred on Sunday - Iran's claim of a shoot-down of a U.S. drone, and an explosion outside the British embassy in Bahrain - may have been unrelated. But they appear to add to growing evidence that an escalating covert war by the West is under way against Iran, and that Tehran is retaliating with greater intensity than ever. Asked whether the United States, in cooperation with Israel, was now engaged in a covert war against Iran's nuclear program that may include the Stuxnet virus, the blowing-up of facilities and the assassination or kidnapping of scientists, one recently retired U.S. official privy to up-to-date intelligence would not deny it.