well as hostile aircraft by giving them a "shutdown" order in which the systems turn off one by one. It is also used to send false messages to hostiles, to place the tide of battle in the favor of America. The technology is later reverse-engineered by the Russian Federation to shut down American antiballistic missile satellites from a tracking station at Socotra Island, Yemen. Cyberwarfare has moved from a theoretical idea to something that is now seriously considered as a threat by modern states. In a similar but unrelated series of incidents involved various groups of hackers from India and Pakistan who hacked and defaced several websites of companies and government organizations based in each other's country. The actions were committed by various groups based in both countries, but not known to be affiliated with the governments of India or Pakistan. The cyber wars are believed to have begun in 2008 following the Mumbai attacks believed to be by a group of Indian cyber groups hacking into Pakistani websites. Hours after the cyber attacks, a number of Indian websites (both government and private) were attacked by groups of Pakistani hackers, claiming to be retaliation for Indian attacks on Pakistani websites. The back and forth attacks have persisted on occasions since then. Doomsday machines A doomsday machine is a hypothetical construction that could destroy all life, either on Earth or beyond, generally as part of a policy of mutually assured destruction. In Fred Saberhagen's 1967 Berserker stories, the Berserkers of the title are giant computerized self-replicating spacecraft, once used as a doomsday device in an interstellar war aeons ago, and having destroyed both their enemies and their makers, are still attempting to fulfil their mission of destroying all life in the universe. The 1967 Star Trek episode "The Doomsday Machine" written by Norman Spinrad, explores a similar theme. Alien doomsday machines are common in science fiction as "Big Dumb Objects", McGuffins around which the plot can be constructed. An example is the Halo megastructures in the video game franchise Halo, which are world-sized doomsday machines that when fired, eliminate all sentient life in three radii of the galactic center, a minimum effective range of 25,000 light-years in every direction. The sentient weapon The science-fiction themes of autonomous weapons systems and the use of computers in warfare date back to the 1960s, often in a frankensteinian context, notably in Harlan Ellison's 1967