IN THE pantheon of Russian intelligence, the KGB is king. It fills the ranks of cinematic and literary villains, from John Le Carré's spymaster Karla to the sleeper agents of “The Americans”, a TV show. But a different set of spies is now hogging the limelight. The GRU, the intelligence arm of Russia's armed forces, has been caught up in almost all the crises involving the country in recent years, from the annexation of Crimea, to the downing of a passenger aircraft over Ukraine, to the attempted murder of Sergei Skripal, a former spy, in Salisbury. Who are these hyperactive military spooks?