I found the article pretty informative.
The Private Soldiers Who Fight in America’s Name.
By Andrea Mazzarino / TomDispatch
The way mercenary leader Yevgeny Prigozhin and his private army have been waging a significant part of Vladimir Putin’s war in Ukraine has been well covered in the American media, not least of all because his firm, the Wagner Group, draws most of its men from Russia’s prison system. Wagner offers “freedom” from Putin’s labor camps only to send those released convicts to the front lines of the conflict, often on brutal suicide missions.
At least the Russian president and his state-run media make no secret of his regime’s alliance with Wagner. The American government, on the other hand, seldom acknowledges its own version of the privatization of war — the tens of thousands of private security contractors it’s used in its misguided war on terror, involving military and intelligence operations in a staggering 85 countries.
At least as far back as the Civil War through World Wars I and II, the Korean and Vietnam Wars, and the first Gulf War, “contractors,” as we like to call them, have long been with us. Only recently, however, have they begun playing such a large role in our wars, with an estimated 10% to 20% of them directly involved in combat and intelligence operations...............