Against the backdrop of military clashes, between 9 January and 20 February 1978, Vietnamese Deputy Foreign Minister Phan Hien made several trips to Beijing to hold discussions with representatives of the Kampuchean government, which ultimately proved to be fruitless. On 18 January 1978, China attempted to mediate between Kampuchea and Vietnam when Vice Premier Deng Yingchao (widow of Zhou Enlai) travelled to Phnom Penh, where her effort was met with strong resistance by Kampuchean leaders. Meanwhile, Vietnamese government officials began conducting secret meetings with So Phim, the Khmer Rouge leader in Kampuchea's Eastern Military Zone, to plan a military uprising backed by Vietnam. During that same period, military setbacks experienced by the KRA in the Eastern Military Zone prompted Pol Pot to label the region as a "nest of traitors".