What's the noun for sabotager? Here's the word you're looking for.
sabotage
A deliberate action aimed at weakening an enemy through subversion, obstruction, disruption, and/or destruction.
(military) An act or acts with intent to injure, interfere with, or obstruct the national defense of a country by willfully injuring or destroying, or attempting to injure or destroy, any national defense or war materiel, premises, or utilities, to include human and natural resources.