Critics of private military contractors sometimes claim that hiring "mercenaries" increases the risk of a military coup against the government. Perhaps private contractors don't have the same degree of loyalty to the state as the uniformed military does.
It is indeed true that mercenaries have sometimes launched coups against the governments that hire them (though most of the cases date back to Renaissance Italy or even earlier). However, the argument is another example of the fallacy I noted in my previous post: failing to apply the same standards to both private and governmental forces. Critics who claim that private contractors pose a special threat in regards to coups usually ignore the long and extensive history of military coups launched by government forces. Many of these coups are far more recent than any similar action by mercenaries. Virtually every country in Latin America and Africa has had at least one coup launched by government military forces since World War II. And they are far from unknown in many other parts of the world.
Moreover, there is some reason to fear that government military forces are actually more likely to launch a successful coup than private ones. Government forces usually have greater perceived legitimacy with the public than mercenaries and can more easily portray themselves as representing the "true" will of the nation against a supposedly corrupt civilian political establishment. That is in fact the usual propaganda line of military coup leaders in Latin American states. It is much harder for mercenaries to make similar claims in a believable way.
In the United States, I think there is very little danger of a coup by either private or government forces. Thus, this issue should not play a significant role in our debate. In some other countries, however, the issue is more significant. And it is important to properly weight the risks on each side.