By resolution 59/26 of 22 November 2004, the UN General Assembly declared 8–9 May as a time of remembrance and reconciliation and, while recognizing that Member States may have individual days of victory, liberation and commemoration, invited all Member States, organizations of the United Nations System, non-governmental organizations and individuals to observe annually either one or both of these days in an appropriate manner to commemorate victims of the Second World War.
The Assembly stressed that this historic event established the conditions for the creation of the United Nations, designed to save succeeding generations from the scourge of war, and called upon the Member States of the United Nations to unite their efforts in dealing with new challenges and threats, with the United Nations playing a central role, and to make every effort to settle all disputes by peaceful means in conformity with the Charter of the United Nations and in such a manner that international peace and security are not endangered.
On 2 March 2010, by resolution 64/257, the General Assembly invited all Member States, organizations of the United Nations system, non-governmental organizations and individuals to observe these days in an appropriate manner to pay tribute to all victims of the Second World War. A special solemn meeting of the General Assembly in commemoration of all victims of the war was held in the second week of May 2010, marking the sixty-fifth anniversary of the end of the Second World War.
Source: un.org