The Stasi also worked as an intelligence agency abroad, using espionage and covert operations in foreign countries. Under its long-time head Markus Wolf it got a reputation as one of the most effective intelligence agencies of the Cold War. After German reunification in 1990, many Stasi officials were prosecuted for their crimes. The files that the Stasi had kept on millions of East Germans were laid open. Now citizens can see their personal files on request; these files are kept by the Federal Commissioner for the Stasi Archives.