These various constituencies so often work in concert with one another that we've almost ceased to find it noteworthy when the front men for such collaborations lie, dissemble, misrepresent, bullshit, and scheme to protect every last dollar in defense accounts. We're not even surprised when they conspire to shame their critics and ruin careers.
All of which leads me to wonder whether Robert Kagan and Jennifer Rubin understand precisely what is meant by the term "constituency," at least in the sense of budgets. Sure, entitlements have a clear domestic constituency: the citizens who get checks in the mail, the representatives they elect, and the businesses and organiziations that are supported by the dissemination of those funds. Does Kagan really fail to see that defense dollars seep into society and influence people in the same way?
(Graph from Center for Responsive Politics, whose data for this year was downloaded on July 5th.)