Compellence and deterrence can fail, however. If compellence and deterrence fail, states may go to war, but even during war, states have choices. They choose the type of weaponry (nuclear or nonnuclear, strategic or tactical, conventional or chemical and biological), the kind of targets (military or civilian, city or country), and the geographic locus (city, state, region) to be targeted. They may choose to respond in kind, to escalate, or de-escalate. In war, both implicit and explicit negotiation takes place, over both how to fight the war and how to end it. We will return to a discussion of war in Chapter 8.