Souphanouvong retired from all his posts in March 1991, heralding a period of major political and economic reform. A new constitution was adopted in August 1991, under which elections for a new National Assembly took place in December 1992. A period of economic reform began as Laos sought to emulate the changes effected by its larger neighbours. The country's relative isolation and lack of resources has made this difficult. Several regional economic co-operation agreements have been reached with Thailand, Cambodia and Vietnam, and Laos has been admitted to the Association of South East Asian Nations, the former anti-communist regional bloc which has since reinvented itself as an economic organisation. In 1995, the Americans relaxed their aid embargo which dated back to the 1975 revolution. These developments were unfortunately offset by the 1997 Asian financial crisis which brought about a collapse in the value of the kip.