Building cannons and swords has never been as profitable as night vision goggles, tanks, body armor, aircraft carriers, missiles, computer systems, etc. Not to mention all the wonderful American contractors that want to get into the act with all their foreign infrastructure building.
Also, it's our desire for commerce with these countries that lead to us having a military presence. Just look @ E. Asia or Saudi Arabia.
Commerce with all is the #1 motivation behind all wars of the 19th, 20th, and 21st century. One merely needs to type IMPERIALISM into google to find out how out of control commerce has become.