Je crois bien que l’unique fois précédente, c’était en janvier 1950 lorsque l’Union soviétique mit en œuvre la « politique de la chaise vide » qui rendit possible l’intervention de l’ONU en Corée du Sud (résolutions 83 et 84 de juillet 1950)…
Politique du siège vide (URSS) - Wikipédia
▻http://fr.wikipedia.org/wiki/Politique_du_si%C3%A8ge_vide_(URSS)
et surtout
United Nations Security Council veto power - Wikipedia, the free encyclopedia
▻http://en.wikipedia.org/wiki/United_Nations_Security_Council_veto_power
In 1950 the Soviet Union missed one important opportunity to exercise its veto power. The Soviet government had adopted an “empty chair” policy at the Security Council from January 1950, owing to its discontent over the UN’s refusal to recognize the People’s Republic of China’s representatives as the legitimate representatives of China, and with the hope of preventing any future decisions by the Council on substantive matters. Despite the wording of the Charter (which makes no provisions for passing resolutions with the abstention or absence of a veto-bearing member), this was treated as a non-blocking abstention. This had in fact already become Council practice by that time, the Council having already adopted numerous draft resolutions despite the lack of an affirmative vote by each of its permanent members. The result of the Soviet Union’s absence from the Security Council was that it was not in a position to veto the UN Security Council resolutions 83 (27 June 1950) and 84 (7 July 1950) authorising the US-led military coalition in Korea which assisted South Korea in repelling the North Korean attack.