Chinese leader Xi Jinping has made a rare trip to Tibet and hailed the crushing of “separatism” in the once-restive region, as Beijing prepares for a looming struggle over the successor of the aging and exiled Dalai Lama and the hearts and minds of millions of Tibetans.

Chinese leader Xi Jinping called for his government to tighten its ethnic-assimilation campaign during a rare visit to Tibet, throwing a spotlight on a region that’s also been a source of tension with India even as the rivals improve ties.

A power struggle is taking shape over choosing a successor to the 90-year-old Buddhist leader. In a trip to Tibet’s capital, China’s leader emphasized maintaining Beijing’s control.