Sherathang. However, the Chinese did not take up the construction of the road on their side at the time. The Dalai Lama, Tenzin Gyatso, used this pass to travel to India for the 2,500th birthday celebration of Gautama Buddha, in the autumn of 1956. After the People's Republic of China took control of Tibet in 1950 and suppressed a Tibetan uprising in 1959, the passes into Sikkim became a conduit for refugees from Tibet. During the 1962 Sino-Indian War, Nathu La witnessed skirmishes between soldiers of the two countries. Shortly thereafter, the passage was sealed and remained closed for more than four decades. During the Indo-Pakistani War of 1965, China exerted pressure on India diplomatically and militarily. In September 1965, China reinforced Yatung and nearby mountain passes with another infantry regiment. India also had a build-up in this area. On the south-eastern front of Sikkim the four passes of Nathu La, Jelep La, Cho La and Dongju had 9, 37, 1 and 9 Indian positions respectively. This build-up was influenced by the region's proximity to East Pakistan, and the tensions that remained following the 1962 war. Following Chinese pressure, Indian troops at Nathu La and Jelep La received orders to withdraw. Nathu La was under Major General Sagat Singh and he refused to withdraw. As a result, in the coming few days, Jelep La was occupied by the Chinese while Nathu La remained defended under India. The coming months saw both sides tussle over dominance in Chumbi Valley. Numerous Indian incursions were reported by Chinese sources. At Nathu La, differing perceptions of the Line of Actual Control among frontline troops on both sides factored in to the increasing tensions. Trench digging, laying of barbed wires, patrolling, celebrating Independence Day, every action became contentious. Between 7 and 13 September 1967, China's People's Liberation Army (PLA) and the Indian Army had a number of border clashes at Nathu La and Cho La, including the exchange of heavy artillery fire. Numerous casualties were reported on both sides. In 1975, following a referendum, Sikkim acceded to India and Nathu La became part of Indian territory. China, however, refused to acknowledge the accession, but the two armies continued to maintain informal communication at the border despite the freeze in diplomatic relations. In 1988 the visit of Prime Minister Rajiv Gandhi to China marked the beginning of fresh talks between the two countries. 2006 re-opening In