When the Pentagon wants to mislead the public about where US troops are, generally speaking, they just lie. Yet sometimes the number of troops is just too big to claim as a rounding error, and questions start happening.
Pentagon spokesman Col. Rob Manning, on the one hand, presented this as an “operational security” and “denying the enemy any advantage,” including, it seems providing any specifics on who “the enemy” at this point even is. At the same time, Manning presented this as simply a limitation of the Pentagon’s current capabilities, and that there is literally “no personnel system” in the Pentagon that tracks where everyone is, and they just stick everyone else in “unknown” so the number of troops they officially have balances out with the number of troops deployed in actual, real places.
Pentagon spokesman Eric Pahon went a step further, saying that the figures are flat out fiction, and were “not meant to represent an accurate accounting of troops currently deployed to any location. They should not be relied upon for a current picture of what is going on.”
Secretary of Defense James Mattis suggested that the situation was complicated, but also that he wasn’t entirely comfortable with the lack of accounting for troops abroad, saying at some point he was going to try to put everything together and figure out where everyone really is. Source: