In the 1960s and 1970s, the governments of Argentina, Brazil, Chile, and Uruguay were overthrown or displaced by U.S.-aligned military dictatorships. These dictatorships detained tens of thousands of political prisoners, many of whom were tortured and/or killed (on inter-state collaboration, see Operation Condor). Economically, they began a transition to neoliberal economic policies. They placed their own actions within the United States Cold War doctrine of "National Security" against internal subversion. Throughout the 1980s and 1990s, Peru suffered from an internal conflict (see Túpac Amaru Revolutionary Movement and Shining Path). Revolutionary movements and right-wing military dictatorships have been common, but starting in the 1980s a wave of democratization came through the continent, and democratic rule is widespread now. Allegations of corruption remain common, and several nations have seen crises which have forced the resignation of their presidents, although normal civilian succession has continued.