Republic of YemenAlthough the governments of the PDRY and the YAR declared that they approved a future union in 1972, little progress was made toward unification, and relations were often strained. In 1979, simmering tensions led to fighting, which was only resolved after Arab League mediation. The goal of unity was reaffirmed by the northern and southern heads of state during a summit meeting in Kuwait in March 1979. However, that same year the PDRY began sponsoring an insurgency against the YAR. In April 1980, PDRY President Abdul Fattah Ismail resigned and went into exile. His successor, Ali Nasir Muhammad, took a less interventionist stance toward both the YAR and neighboring Oman. On January 13, 1986, a violent struggle began in Aden between Ali Nasir Muhammad and the returned Abdul Fattah Ismail and their supporters. Fighting lasted for more than a month and resulted in thousands of casualties, Ali Nasirs ouster, and Ismails death. Some 60,000 persons, including Ali Nasir and his supporters, fled to the YAR.In May 1988, the YAR and PDRY governments came to an understanding that considerably reduced tensions including agreement to renew discussions concerning unification, to establish a joint oil exploration area along their undefined border, to demilitarize the border, and to allow Yemenis unrestricted border passage on the basis of only a national identification card.In November 1989, the leaders of the YAR (Ali Abdullah Saleh) and the PDRY (Ali Salim al Baidh) agreed on a draft unity constitution originally drawn up in 1981. The Republic of Yemen (ROY) was declared on May 22, 1990. Saleh became President, and al Baidh became Vice President.