Since well before 11 September 2001, Russia has faced a significant threat of terrorism from radical Islamist groups based in Chechnya and other parts of the North Caucasus region. First as prime minister under Yeltsin, then as president, Vladimir Putin cited terrorism as justification for a comprehensive series of measures centralising power. These measures included appointing presidential envoys to federal super-districts, ending the direct election of regional governors, eliminating single-member district seats from the State Duma, expanding state control over the mass media, and tightening controls over public political activity. Efforts by parliament to assert oversight power over the security agencies, such as through investigations of their actions in the Beslan crisis, were effectively blocked. The terrorist threat thus created opportunities for President Putin to pursue a political agenda that aggrandised presidential power at the expense of the Duma and other federal-level institutions, as well as regional governments, the mass media, and civil society.