The Soviet Union and Guinea-Bissau established diplomatic relations on 6 October 1973. In 1973, the Soviets began to supply the PAIGC with Strela 2 ground-to-air missiles for use in its war with the Portuguese. On 21 February 1975, a number of agreements were signed by the two states, covering economic, technical, cultural and scientific co-operation, a trade agreement and an air services agreement. From 1974 to 1983, Soviet Union was the sole supplier of arms to Guinea-Bissau.