Codename: TSV (The Silent Victory)
All-terrain (walls, drains) rat-sized centipede. Can relay to a remote terminal, where an operator marks hostiles. Anaesthetic-coated burrowing nanomachines are fired at the neck, which - on command - chew through the medulla oblongata. One drone carries enough to annihilate a battalion. Zero collateral, completely effective. A silent victory.