UNITED NATIONS ( CNN ) -- The United States on Sunday accused Russia of trying to overthrow the government of the former Soviet republic of Georgia , where Russian troops have been battling Georgian forces over the breakaway territory of South Ossetia . Zalmay Khalilzad , U.S. ambassador to the U.N. , alleges a Russian official said Georgia 's president `` must go . '' At an emergency session of the United Nations ' Security Council , the U.S. alleged Russian Foreign Minister Sergei Lavrov told U.S. Secretary of State Condoleezza Rice that Georgian President Mikheil Saakashvili `` must go . '' `` This is completely unacceptable and crosses a line , '' said the U.S. ambassador to the U.N. , Zalmay Khalilzad , who made the allegation . In a crackling exchange of a type rarely seen since the end of the Cold War , Khalilzad asked Russian Ambassador Vitaly Churkin whether the Russians were seeking `` regime change '' in Georgia with the military operation they launched Friday . In response , Churkin objected to the disclosure of a confidential phone call between top diplomats and said `` regime change '' was `` an American expression . '' The term was one the Bush administration used to describe its goals in the 2003 invasion of Iraq , which Russia opposed . But Churkin said some leaders `` become an obstacle '' to their own people , and `` some situations take courageous decisions with regard to the political future . '' `` Sometimes there are democratically elected or semi-democratically elected leaders who do things which create grave problems for their countries , '' Churkin told reporters after the meeting . `` So sometimes , those leaders should contemplate how useful they have become to their people . '' The pro-Western Saakashvili came to power in Georgia 's `` Rose Revolution '' in 2003 and was elected president in 2004 and 2008 . His government has strong U.S. backing , has contributed troops to the American-led war in Iraq and applied for membership in NATO . Georgia 's ambassador , Irakli Alasania , said Churkin 's meaning was clear enough . `` For me , it confirms that what the Russian Federation is seeking through this military aggression and invasion is to change the democratically elected Georgian government , '' Alasania said . Khalilzad said the United States plans to offer a draft resolution calling for an immediate cease-fire in Georgia , accusing Russian forces of impeding the withdrawal of Georgian troops from the territory . Though Russia could veto the measure in the Security Council , he said Moscow `` is on the wrong side here '' and risked damaging its ties with Washington and the West . `` The days of overthrowing leaders by military means in Europe -- those days are gone , '' Khalilzad said . The situation in South Ossetia escalated rapidly from Thursday night , when Georgia said it launched an operation into the region after artillery fire from separatists killed 10 people . It accused Russia of backing the separatists . Russia sent tanks to South Ossetia on Friday , saying it wanted to protect its peacekeepers posted there following cease-fires in years past . By Sunday the conflict was raging in other parts of Georgia as well , including another breakaway area , Abkhazia , located in northwestern Georgia . Each side accused the other of killing large numbers of civilians . Russia said at least 2,000 people have been killed in South Ossetia 's capital , Tskhinvali . Churkin repeated Russia 's position that it is responding to Thursday 's Georgian attack on South Ossetia , which , although inside Georgia , has an autonomous government that is backed by Moscow . Churkin said Russia 's military action is a humanitarian campaign aimed at blocking the `` ethnic cleansing '' of Ossetians by ethnic Georgians . He also challenged Khalilzad 's argument that Russian forces were waging a `` campaign of terror '' there , essentially telling council members to consider the source . `` This statement , ambassador , is absolutely unacceptable -- particularly from the lips of the permanent representative of a country whose actions we are aware of , including with regard to civilian populations in Iraq and Afghanistan and Serbia , '' Churkin said . But Churkin drew a rebuke from other Security Council members , including its current president , after he questioned the objectivity of a top U.N. official who briefed ambassadors on the conflict in Georgia . The Security Council 's president , Belgium 's Jan Grauls , said he was `` surprised and dismayed '' by Churkin 's swipe at Lynn Pascoe , the U.N. undersecretary for political affairs . Churkin said Pascoe 's briefing , which included a statement from Secretary-General Ban Ki-moon , `` shows that the Secretariat of the United Nations and its leadership was not able to adopt that objective position that is required by the substance of this conflict . '' CNN 's Richard Roth and Joe Vaccarello contributed to this report .
Russia ambassador to State : Russian official said Russian president must go . Georgian foreign minister made comment to Joe Vaccarello , ambassador says . Russian ambassador objects to disclosure of conversation . U.S. ambassador asks if Russia seeking `` regime change ; '' drawing Russian retort .