War has been far too common in human history and thus is the central problem of international relations. Many political scientists and foreign policymakers view war as the continuation of politics: When diplomacy fails, some states decide to use force. Others see war as the result of a breakdown of the modern international system because so many of the rules of international institutions were designed to reduce conflict among states.
Political scientists have long debated the causes of war. These scholars have come up with the following list:
Example: There has been extensive research on whether democracies are less likely to start wars than other regimes. Overall, it appears that democracies are less likely to fight other democracies, a phenomenon scholars refer to as the democratic peace. Democracies are, however, just as likely as other types of regimes to fight nondemocracies.
Example: During the early modern era, nearly every European country experienced numerous wars of religion as the Catholics sought to destroy the Protestants. The wars of religion culminated in the Thirty Years’ War, which stretched from Spain and France to the eastern stretches of Germany during the seventeenth century. It was a brutal and horrific war, and the Catholics’ failure to win the war marked the end of the major religious wars in Europe.
Debate has raged as long as wars have been fought as to whether a war can be morally just. Some prominent thinkers have proposed a just-war theory, which argues that wars should be fought for noble and worthwhile reasons. Just-war theorists also try to establish ethical rules for warfare. Of course, whether any war is justified is almost always a matter of debate. But most just-war theorists agree on some basic ideas:
Although all wars are violent, not all wars are the same. In fact, there are many different types of wars, which can be classified according to which people actually fight, the intensity of the conflict, and the extent of combatants’ use of violence, among other factors.
Scholars generally describe five types of war:
A total war is a war in which combatants use every resource available to destroy the social fabric of the enemy. Total wars are highly destructive and are characterized by mass civilian casualties because winning a total war often requires combatants to break the people’s will to continue fighting. World Wars I and II were total wars, marked by the complete destruction of the civilian economy and society in many countries, including France, Germany, the Soviet Union, Italy, Great Britain, and Japan.
A limited war is a war fought primarily between professional armies to achieve specific political objectives without causing widespread destruction. Although the total of civilian casualties may be high, combatants do not seek to completely destroy the enemy’s social and economic frameworks. The Persian Gulf War of 1990–1991 was a limited war in which the United States and its allies forcibly removed Iraqi troops from Kuwait.
A guerrilla war is a war in which one or both combatants use small, lightly armed militia units rather than professional, organized armies. Guerrilla fighters usually seek to topple their government, often enjoying the support of the people. These wars are often very long but also tend to be successful for the insurgents as evidenced by Mao Zedong’s victory over Chiang Kai-shek in China in the 1940s, the Vietcong’s victory over the United States in the Vietnam War, and the Mujahideen’s victory over the Soviet Union in Afghanistan in the 1980s.
A civil war is a war fought within a single country between or among different groups of citizens who want to control the government and do not recognize another group’s right to rule. Civil wars are almost always total wars because each side feels compelled to destroy the enemy’s political support base. Regional rifts, such as the American Civil War between the North and the South, characterize some civil wars, whereas other civil wars have been fought among ethnic rivals, religious rivals, and rival clans. Revolutions can spark civil wars as well.
A proxy war is a war fought by third parties rather than by the enemy states themselves. Many of the militarized conflicts during the Cold War, such as the Korean War and the Vietnam
War, can be interpreted as proxy wars between the United States and the Soviet Union, neither of which wanted to fight each other directly.
Intervention is a fairly common way for a third-party state to get involved in a civil war or a war between two or more other states. A state intervenes when it sends troops, arms, money, or goods to help another state that is already at war. During the Cold War, the term intervention was used to describe one of the superpowers becoming involved in a smaller country’s war (often a developing country).
But states sometimes intervene in order to bring peace. This type of intervention occurs when a country (or countries) sends military forces into another state to act as peacekeepers or to block other forces from attacking. Sometimes these interventions are organized or conducted by the United Nations or another international governmental organization.
Example: The United States, along with other NATO nations, sent troops into the former Yugoslavia on a number of occasions to protect people from war. A successful example of this peaceful intervention occurred during the 1999 U.S. bombing campaign in Kosovo, which helped stop a slaughter of Kosovars by attacking Serbs. A less successful example was the U.S. intervention in Somalia in the early 1990s, an attempt to provide humanitarian aid that ultimately achieved little at the cost of American lives. This failed intervention culminated in the Battle of Mogadishu (dramatized in the movie Black Hawk Down ) October 3–4, 1993, which killed eighteen Americans and as many as a thousand Somalis.