Sino-Soviet relations cooled during 1958 to 1959. China was upset by the lack of Soviet assistance in quelling the Tibetan uprisings in 1959 and against the escape of Dalai Lama to India. The Soviet Union later refused support for China in the Sino-Indian War of 1962. Khrushchev was unnerved at Mao's relatively nonchalant view on nuclear war. The Soviet Union was also engaged in test ban negotiations with the United States in 1959 in order to relax Soviet-American tensions, directly inhibiting the delivery of a prototype to China. Broader disagreements between Soviet and Chinese communist ideologies escalated mutual criticism. The Soviets responded by withdrawing the delivery of a prototype bomb and over 1,400 Russian advisers and technicians involved in 200 scientific projects in China meant to foster cooperation between the two countries.