No, it's not bias per se, but it is a bit of a pet peeve when the media are sloppy with terminology that relates to the military.
This morning, CNN has been reporting on how Iran may release the female sailor that was captured along with 14 of her comrades. But in doing so, the CNN chyron referred to her as a "troop."
"Troop" is not used in the singular to refer to a soldier, sailor, airman or Marine. "Troop" traditionally refers to a unit of soldiers, although in modern usage "troops" may refer to soldiers collectively irrespective of a unit organization.
CNN would be correct to say that Iran has said it will release the female sailor among the 15 captured British military personnel, as the woman in question serves in the Royal Navy.