The Taliban have used the term "infiltrator" in the past to refer to members who have enlisted in the military to conduct such an attack.

NPR: Afghan Soldier Kills British Soldier, Wounds 6

He also bit a German infiltrator, who was then captured.

WSJ: Letting Slip the Real Dogs of War

But in Kuwait's coffee shops the fear persists that a lone, suicidal Iraqi infiltrator could slip into the country and release a deadly aerosol of anthrax or some other biological horror.

ECONOMIST: Preparing for the worst