 However, fighting erupted between North Yemen and South Yemen in October of that year; North Yemen was supplied by Saudi Arabia and South Yemen by the USSR.The fighting was short-lived, and led to the Cairo Agreement of October 28, 1972, which put forward a plan to unify the two countries.Fighting broke out again in February and March 1979, with South Yemen allegedly supplying aid to rebels in the north through the National Democratic Front and crossing the border.