United Nations Security Council resolution 642, adopted unanimously on 29 September 1989, after recalling resolutions 598 (1987), 618 (1988) and 631 (1989) and having considered a report by the Secretary-General Javier Pérez de Cuéllar on the United Nations Iran–Iraq Military Observer Group, the Council decided:
(a) to call on both Iran and Iraq to implement Resolution 598;
(b) to renew the mandate of the United Nations Iran–Iraq Military Observer Group for another six months until 31 March 1990;
(c) to request the Secretary-General to report on the situation and the measures taken to implement Resolution 598 at the end of this period.