Who is the "doer" of US foreign policy?

First, read this article

The basic question raised in the post is worth pondering: with all of the development overlapping with military conflict in the 21st century who or what is the appropriate agency to conduct applied foreign policy? The standard answer for a long time was the State Dept and clearly that is no longer the answer. In the past 10 years the military has taken an increasing roll in applying policy on the ground. Why is this an issue? There are many reasons but the first ones that come to mind are:
1. It's bad public relations. I don't care how you spin a big military presences in development projects it ALWAYS looks like we're trying to create an empire.
2. People sign up to the military because they love our country and want to defend it, possibly by by killing shit (an huge oversimplification which I hope you'll forgive me). I don't think those people are necessarily suited to doing good development work.

What should we do? I don't think throwing more money at the State department is the best way to go. The conflicts that loom in the future seem like they'll require a combination of hard military action and follow up development work. I think the best way to go is something like the way Thomas Barnett has advocated.

Summary from wikipedia:

1. In recognition of its dual role, the US military should organize itself according to two functions, the "Leviathan" and the "System Administrator."
   • Leviathan's purpose is employ overwhelming force to end violence quickly. It will take out governments, defend Core countries, and generally do the deterrence work that the US military has been doing since the end of WWII. The Leviathan force is primarily staffed by young aggressive personnel and is overwhelmingly American.
   • The SysAdmin's purpose is to wage peace: peacekeeping, nation building, strengthening weak governments, etc. The SysAdmin force is primarily staffed by older, more experienced personnel, though not entirely (he would put the Marines in SysAdmin as the " Mini-me Leviathan"). The sys Admin force would work best as a Core-wide phenomenon.

Thoughts?