The UN General Assembly, in December 2009, adopted a resolution calling for a UN Conference on Sustainable Development (UNCSD, also referred to as Rio+20) to be convened in Brazil in 2012. This meeting will mark the 20th anniversary of the UN Conference on Environment and Development (UNCED), which convened in Rio de Janeiro, Brazil. The General Assembly resolution specifies that a three-day PrepCom should convene in May 2010, a two-day PrepCom should convene in March 2011, and a three-day PrepCom should convene immediately before the UNCSD (PrepCom III). On 4 November 2011, Dilma Rousseff, President of Brazil, announced a proposal to change the dates to 13-15 June 2012 for PrepCom III and 20-22 June 2012 for the UNCSD, in order to allow for highest-level participation. The previously scheduled dates were 28-30 May 2012 for PrepCom III and 4-6 June 2012 for the UNCSD.