UNITED NATIONS -LRB- CNN -RRB- -- The rift between Russia and Western powers over Georgia burst back into full view on the U.N. Security Council when Russia vetoed a resolution that would have extended the U.N. observer mission in Georgia . The observer force had been in existence since 1993 , but Russia claims that the mission was invalidated by last year 's conflict over breakaway regions in Georgia . `` The U.N. mission 's previous mandate has actually ceased to exist in the wake of Georgia 's aggression against South Ossetia last August , '' said Vitaly Churkin , Russia 's U.N. ambassador , who said it was `` unacceptable '' to extend the mission . After the veto Monday night , a statement from the office of U.N. Secretary-General Ban Ki-moon said the U.N. would `` take all measures required to cease the operations of the United Nations Observer Mission in Georgia effective 16 June . '' Ban `` will consult with his senior advisors and his special representative on the immediate next steps , '' the statement said . Russia and Georgia fought a five-day war last August over the breakaway Georgian provinces of South Ossetia and Abkhazia -- the first time Russia sent troops abroad in anger since the fall of the Soviet Union in 1991 . Both sides blame the other for starting the conflict . Western powers , including the United States , the United Kingdom and France backed the Georgian government in a conflict that rekindled Cold War sentiments . The European Union launched a probe to determine how the war began that is due to be completed by the end of next month . The crux of the controversy remains Georgia 's territorial integrity . As a result of last year 's war , Russia now considers South Ossetia and Abkhazia sovereign nations independent from Georgia . Russia has no international support for that position aside from the nation of Nicaragua . The Georgian ambassador to the United Nations , Kakha Lomaia , addressed the Security Council following the vote , saying his nation deeply regrets the apparent end of the mission . He called Russia 's position `` unconstructive . '' The statement from Ban 's office added , `` the Secretary-General regrets that the Security Council has been unable to reach agreement on the basis of a package of practical and realistic proposals he submitted to the Security Council aimed at contributing to a stabilization of the situation on the ground . ''