When the concerned States fail in settling a dispute by peaceful means, forcible or coercive means are adopted. These are Retorsion, then Reprisal, Intervention, Blockade war.According to J.G.Starke, retorsion is relation by a state against Retorsion discourteous or inequitable acts of another state such retaliation.
Before opting coercive means of dispute settlement, States try following methods of international dispute settlement by amicable means. According to Oppenheim, "Negotiation is an intercourse between two or more states as is initiated and directed for the purpose of effecting and understanding between them or settling a dispute.
War is a state of organized, armed, and often prolonged conflict carried on between states, nations, or other parties typified by extreme aggression, social disruption, and usually high mortality. The set of techniques used by a group to carry out war is known as warfare. An absence of war is usually called peace.