Sometimes it is morally imperative to fight against overwhelming odds, as resistance fighters did in World War II. Also this condition may give large nations free rein to bully small ones because they could not win a war. It also may cause a country to surrender in a war it might actually win. Weak countries have won wars against powerful ones – look at the American Revolution. Finally, the point at which a war became unwinnable, and therefore unjust by this definition, is often only identifiable with hindsight – consider the Soviet occupation of Afghanistan, or the American involvement in Vietnam.