This period was also marked by efforts to expand the jurisdiction and mandate of the committee between 1958 and 1975, which did not receive the consent of all four riparians. However, these efforts culminated, in January 1975, in the adoption of a 35-article "Joint Declaration of Principles for Utilization of the Waters of the Mekong Basin" by the sixty-eighth session of the Mekong Committee, prohibiting the "unilateral appropriation" without "prior approval" and "extra-basin diversion" without unanimous consent. However, no committee sessions were held in 1976 or 1977, as no plenipotentiary members had been appointed by Cambodia, Laos, or Vietnam—all of which experienced regime change in 1975.