NATO, as we know it today, is a de facto bulwark against Russian (née Soviet) expansionism into Western Europe and potentially elsewhere. It must have come as a complete surprise when France, Great Britain, and the United States all received letters of intent from the Soviet Foreign Ministry about joining the alliance.
Originally a political alliance in Western Europe when it was formed in 1949, NATO became a solid military alliance as well when the Korean War made the idea of Communist expansion by force all too real. The same year the Soviets detonated their first nuclear weapon, the West formed an alliance to neutralize that threat. But before the Soviet-dominated countries of Eastern Europe formed the Eastern Bloc in 1955, Russia made an attempt to join NATO.
Guess who's coming to dinner.
Longtime Soviet dictator Joseph Stalin finally died in 1953 and Nikita Khrushchev was the new communist sheriff in town. So in 1954, when Soviets sent the letters of intent to NATO members, there was a renewed spirit of easing tensions. The Soviets reasoned that the aggressive nature of the NATO alliance would be much less dangerous to world peace if their former anti-Hitler ally were allowed to be a member.
Forgot about An-dre.
But in order to join the alliance, the Soviet Union would have to allow NATO to dictate its military planning and allow the basic tenets of democratic freedoms to bloom in all areas under its control. The debate about potentially allowing Russia to join reminded the member states that the alliance was formed to address threats to world peace when the UN couldn't — usually because of Russia's veto power on the Security Council.
Allowing the Russians to have a say in NATO affairs would neutralize NATO the way they neutralized the UN Security Council.
Can't blame them for trying.
NATO told the Russians exactly that when the alliance rejected Russia's application for membership, urging it and other Soviet satellites to allow the UN to do its job in keeping the world secure. It was not an unexpected response for the USSR.
"Most likely, the organizers of the North Atlantic bloc will react negatively to this step of the Soviet government and will advance many different objections. In that event the governments of the three powers will have exposed themselves, once again, as the organizers of a military bloc against other states and it would strengthen the position of social forces conducting a struggle against the formation of the European Defense Community," Soviet Foreign Minister Vyacheslav Molotov wrote.
Nine days later, Russia and those satellites formed the Warsaw Pact, its Eastern Bloc counter-alliance. Europe was officially split for the next 40-plus years.