The OP probably thought of defense in the narrow sense as "the action of defending against or resisting an attack", and not in the broader sense defined as "we’re going to travel halfway around the world to kill a million people because that’s who we are". A common mistake.

That depends greatly on which interests you allow to be defined as "American". The vast majority of American people would have preferred not to be involved in most of our foreign adventures. The rich and powerful thought differently. Is our citizenship determined by the size of our bank accounts?

Invading other countries to take their resources and kill civilians is not defence.

With your logic, Russia is also acting in a defensive manner.