The purpose of our foreign policy should simply be to maximize our security, power, and wealth.
 The USA has pursued a foreign policy directly opposite of those aims since the mid-1930s.
 As I've grown older I've become very skeptical of military aggression, as even if our assaults on foreign countries were carried out in the national interest (they're not) the theoretical benefits are almost never worth the cost.
Allow me some remarks:
 all these purposes are in some kind compulsory for a government of a free state. It is worth to note that those can only be achieved by carefully balancing them in a international concert.
 if your posit was accurate, USA would be a very poor country with little influence. Quite the opposite is reality.
Nevertheless, there are more people in misery than in other developed countries.
But that is a consequence of internal politics and not a lack of successful foreign policy.
 That is very true.
Dress rehearsal for war is usually armed diplomacy that equals blackmail, and often is a fertilizer for devastating conflicts to come.