 Some were transferred to various cultural and educational departments to replace leading cadres who had been labelled "rightists" and sent to work in labour camps.By the early 1970s, Sino-American relations had begun to improve.Mao's workers in the petroleum industry, one of China's few growing economic sectors at the time, advised the Chairman that, in order to consider growth at levels desired by the Party's leadership, large imports of American technology and technical expertise were essential.