I keep hearing reports of so-and-so many troops being deployed here and there in Iraq and Afghanistan. I've talked to several friends that are or were in the armed services because the news media keeps making me scratch my head. Apparently, the word troop has changed its meaning recently.
One of the popular definitions of troop is "an assemblage of persons or things; company; band." Think "Boy Scout Troop." In the new meaning, a troop has been downsized to being one person; a soldier. Thus, troop has become a synonym for soldier. This seems to be meant to depersonalize the people who are serving their country.