The Sino-Albanian split refers to the gradual worsening of relations between Albania and the People's Republic of China in the period 1972–78. Both countries had supported each other in the Soviet–Albanian and Sino-Soviet splits, together declaring the necessity of defending Marxism–Leninism against what they regarded as Soviet revisionism within the international communist movement. By the early 1970s, however, Albanian disagreements with certain aspects of Chinese policy deepened as the visit of Nixon to China along with the Chinese announcement of the ""Three Worlds Theory"" produced strong apprehension in Albania's leadership under Enver Hoxha. Hoxha saw in these events an emerging Chinese alliance with American imperialism and abandonment of proletarian internationalism. In 1978, China broke off its trade relations with Albania, signalling an end to the informal alliance which existed between the two states.