<blockquote>Contractors also encourage mission creep, because contractors don't count as "boots on the ground." Congress does not consider them to be troops, and therefore contractors do not count again troop-level caps in places like Iraq. The U.S. government does not track contractor numbers in war zones. As a result, the government can put more people on the ground than it reports to the American people, encouraging mission creep and rendering contractors virtually invisible.</blockquote>
via <a href="http://www.theatlantic.com/international/archive/2016/08/iraq-afghanistan-contractor-pentagon-obama/495731/">America's Addiction to Mercenaries - The Atlantic</a>.