New details of Moscow's intelligence work in Cuba were disclosed by Vasili Mitrokhin, a former KGB archivist who defected to Britain in 1992. ...Russian KGB officer Nikolai Leonov became "firm friends," with Mr. Castro's younger brother Raul in Prague in 1953 and then worked together with Fidel from 1956 and after he took power in 1959. The book, the second volume of what is known as the Mitrokhin archive, also reveals how Moscow sought to indirectly defeat the United States during the Cold War through large-scale "disinformation" and influence operations in the developing world. "The KGB really believed they could...