Cambodia's relations with China were based on mutual interests. Sihanouk hoped that China would restrain the Vietnamese and the Thai from acting to Cambodia's detriment. The Chinese, in turn, viewed Cambodia's nonalignment as vital in order to prevent the encirclement of their country by the United States and its allies. When Premier Zhou Enlai visited Phnom Penh in 1956, he asked the country's Chinese minority, numbering about 300,000, to cooperate in Cambodia's development, to stay out of politics, and to consider adopting Cambodian citizenship. This gesture helped to resolve a sensitive issue—the loyalty of Cambodian Chinese—that had troubled the relationship between Phnom Penh and Beijing. In 1960 the two countries signed a Treaty of Friendship and Nonaggression. After the Sino-Soviet rift Sihanouk's ardent friendship with China contributed to generally cooler ties with Moscow.