Following the Soviet note of 27 November 1958 which challenged the status quo established by the Potsdam Agreement, the Three Western Powers (UK, US and France) decided on 4th April 1959 to set up a Planning Group, named Live Oak, to prepare plans on land and in the air which would guarantee West Berlin's access and would help assess Soviet's intentions. On 2nd April 1959 and 21st September 1960 respectively, the French and UK Representatives to the North Atlantic Council presented the Three Powers' view on the measures to be taken in case of a crisis and on the need for coordination between NATO and Live Oak. The crisis of 13 August 1961 and the erection of the Berlin wall, resulted in an acceleration of NATO's plans for Berlin Emergency and the adoption of temporary measures to strengthen the Alliance's military machinery. The files at this website, organized by year/volumes consist of formal documents created by the NATO Council, the Military Authorities, SHAPE and the three Western Powers as well as informal notes from the Private Office, the Economic and Finance Division, the Defence and Planning Division and correspondence from delegations.