Are United States military interventions and wars absolutely necessary to preserve democracy and freedom?

I believe it is fair to say that, in most cases, the United States needs to be involved in military interventions or in wars to preserve democracy and freedom. There are several examples that support this position. During the 1920s and the 1930s, the United States and other European countries actively followed an isolationist foreign policy for various reasons. This backfired as aggressive countries, led by dictators such as Hitler and Mussolini, began to take over other countries. One message this whole set of events suggested is that aggression cannot be ignored.
After World War II, the United States, our allies, and, at times, the United Nations took an active role to prevent the spread of communism to non-communist countries. It is fair to say that if the United States, France, and Great Britain did not organize the Berlin Airlift, West Berlin would have fallen into communist hands. The same case can be made in South Korea in 1950. Even with help from the United Nations, South Korea nearly was conquered by communist North Korea. With the help of forces from the United Nations, led by the United States, South Korea remained free and does so to this day. Currently, there is a growing threat from North Korea with its development of nuclear weapons, and the United States is supporting South Korea.
The United States developed the European Recovery Program to help nations that were fighting the spread of communism in Europe after World War II. The United States gave aid to Greece and Turkey to help them avoid being taken over by communist forces. The Cuban Missile Crisis is another example where American involvement was needed. The United States could not allow the Cuban government and the Soviet Union to put missiles with offensive capabilities in Cuba. The United States needed to act to protect the American people and other countries in the Western Hemisphere.
In each of these cases, the United States was acting to preserve freedom and democracy in countries where it already existed and was being threatened by the actions of other countries. It is reasonable to conclude that the United States needs to be involved when threats are made to democratic governments and to freedom.
https://www.history.com/topics/cold-war/berlin-airlift

https://www.history.com/topics/cold-war/cuban-missile-crisis

https://www.thoughtco.com/the-korean-war-an-overview-2360860