The United States of America (USA) and its military allies made various attempts and agreed on a mechanism of consultation between representatives of members of the North Atlantic Treaty Organization (NATO) and Russia before taking the decision on expansion of NATO eastward in view of Russia’s objection to such a move. But they failed to nullify Russia’s national security concerns and apprehensions which emerged because of the proposed NATO expansion. In fact, it was difficult for the West to convince Moscow about the need of NATO expansion amidst the profound changes brought about in the nature of relations between Russia and its Western neighbours as well as the USA in the post-Cold War period. Though President Boris Yeltsin of Russia agreed to allow the expansion of NATO, Moscow has never missed an opportunity to express its disapproval on the expansion of NATO because it undermines Russia’s national security.