In an interview, Obama said:
--Private security contractors put our troops in harm's way(?)
--If you start building a military premised on the use of private contractors and you start making decisions on armed engagement based on the availability of private contractors to fill holes and gaps that over time you are, I believe, eroding the core of our military’s relationship to the nation(?)
--I think you are privatizing something that is what essentially sets a nation-state apart, which is a monopoly on violence(?)
The remark was not all that inscrutable; it was probably something he remembered from an undergrad course, or maybe a law school course, on the history of the European nation state (that is, the centralized territorial nation state).
In the European Middle Ages, in the monarchical states, the police power (so to speak) was decentralized and distributed among feudal lords. As a result, there was often armed conflict between the different lords over duchy boundaries, lines of ruling succession, and other weighty matters. The monarchs had their own small armies, but in times of large conflict had to rely upon the obligation of the feudal lords to aid the monarch, who would, of course, reward victories with additional land, estates, privileges, and so on. In this period, the monarch did not have a monopoly on armed force, that is to say, a monopoly on violence. The historical rise of the territorial nation state brought, as was requisite, the centralization of police power and capability to wage military violence, in the monarch; and concommitently the decline of the police and military powers of the feudal lords. The nation-state is therefore viable, almost as a matter of definition, only when it (first in the person of the monarch, later in the institution of the central secular government) has a monopoly on "violence" inside its territorial boundaries. Other historical wielders of military and police power must deprived of their ability to make violence, so to speak. This, more or less, is what Obama was talking about.
Obama is not correct, however, to assume that the central state's monopoly on police and military power requires it to use its own, paid, standing armed forces in its role as the sole holder of such power. Repeatedly throughout European history, the central state employed mercenaries (I am not stating that Blackwater is a mercenary force). And, of course, assignment of police power to local governmental corporations, who were given the right to employ armed security officers, i.e., police, is also a transfer of the state's monopoly on force (the capability to wage violence, in Obama's terms).
Obama's abbreviated reference to this history of the nation state cannot imply that it is illegitimate of the US to hire private contractors for security work that might entail use of force (or response force), even when they are held immune from prosecution by (in the case at hand) the Iraqi government. And it is difficult to understand how the use of such contractors interrupts the US military's relationship to the nation. The nation has not, by employing contractors, abrogated its authority to cease using such contractors or to regulate their activities. And such contractors are not given authority over the military.
Obama's learnedness has, here, gotten all twisted and confused.
See also: Astute Blogger's excellent discussion of Blackwater--they're not mercenaries.