A Russian Foreign Ministry official has said that Britain has been Russia’s enemy since Ivan the Terrible reigned over Medieval Rus’, in response to reports that London was considering retaliatory cyberattacks against Moscow.

The Sunday Times cited unnamed senior security sources in reporting that the U.K. has tested capabilities to cause mass blackouts, including in the Kremlin, if Russia encroached on neighboring Estonia, intervened in Libya or attacked British troops. The publication cited a source as saying: “This is why cyber is so important; you can go on the offensive and turn off the lights in Moscow to tell them that they are not doing the right things.”