NATO is the right answer. NATO began to take form in the Treaty of Brussels of 1948 as a defensive pact between France, the U.K., Netherlands and Luxemburg against the Soviet threat, but even so the weakened european countries were still threatened by the USSR, by 1949 negotiations between the countries and the U.S. made the pact into a full alliance with the North Atlantic Treaty, called North Atlantic Treaty Organization under the goal, as stated by the organization's first secretary, to "keep the russians out, the americans in and the germans down".
