Not necessarily, a dog may show resource guarding but never be aggressive because the situation never escalates to that point. I have seen many dogs steal every other dog's toys but never get aggressive because the other dogs never challenge him (not worth it!). Any dog may show aggression when guarding a resource if pushed to the limit. That is why punishment and confrontation are the WORST methods to treat aggression in dogs guarding a bed, couch, toy, food or human. This will only make the problem worse (see case study above).