The main reason behind the formation of North Atlantic Treaty Organization (NATO) was to defend themselves against Soviet aggression. It was a treaty that was created by United States of America along with Canada and several western European Nations. The treaty was created in the year 1949. NATO was the first peace time alliance between several countries along with United States of America. The Second World War had devastated several European countries economically and they did not want the Soviets to take advantage of this position.