 In January 1949, the United Nations Security Council called for the release of the Indonesian leaders captured during the police action and for the Dutch to transfer sovereignty to Indonesia by 1 July 1950.In the face of this pressure the Dutch conceded defeat, and insisted on preliminary discussions with the Indonesian republican government.Negotiations between the two sides began on 14 April, but reached deadlock after a week, with Dutch delegation leader Jan Herman van Roijen demanding a cessation of guerrilla warfare and agreement to attend the Round Table Conference by the Indonesians before the republican leadership would be allowed to return to Yogyakarta.