U.S. President George W. Bush urged his European allies in Bucharest, Romania, earlier on Wednesday to meet the request of the ex-Soviet republics to join the program paving the way to membership.
"This will not be unanswered. But we will respond in a pragmatic way, not like little school boys who were hurt and fled their classroom slamming the door to cry in the corner," Sergei Lavrov said.
"We are prepared for various scenarios," he added.
Speaking before the NATO summit, Bush said, "My country's position is clear - NATO should welcome Georgia and Ukraine into the Membership Action Plan."
However, France and Germany and some other countries have been reluctant to admit the two countries into the action plan saying they do not meet accession criteria. They are also unwilling to provoke Russia, relations with which plunged to a post-Cold War low over the bloc's ongoing expansion toward its borders and U.S. missile plans for Europe.
Bush said: "The Cold War is over. Russia is not our enemy. We are looking to a new security relationship with Russia."
Bush also said he remained committed to deploying missiles in Poland and a radar in the Czech Republic and would press Russia to drop its opposition at talks with outgoing President Vladimir Putin in his holiday residence in Sochi on April 6.
He reiterated that missile shield elements in Europe would be designed to contain possible attacks from "rogue" states like Iran, and were not aimed against Russia. Moscow treats the plans as a direct threat to its security.
Bush said the United States and Russia could join hands in missile defense and arms control adding Russian radar stations in Azerbaijan and south Russia, earlier proposed by Moscow as an alternative to new facilities in Europe, could be part of a joint missile defense system.
Russia is currently studying U.S. proposals to ease its missile defense concerns, which it praised as 'measures to raise transparency.' But Lavrov said earlier this month the best way to address Moscow's concerns was to give up the missile shield plans.
Bush and Putin could also meet on the sidelines of the NATO summit to last until April 4.
