But robots, however cleverly programmed, had three weaknesses. One, they were mechanical, so they were vulnerable to water, weather, and the sucking muds of the wilderness, however well sealed they might be made. Two, destroying them outright or turning them off was far less of an ethical problem for troops than slaying living sentients; colonists rarely hesitated to shoot robots when the two forces were even vaguely close to being equal. And three, they were reprogrammable, either to shut them off en masse, or turn them against their masters.
