“World War III” is not a phrase to be casually tossed around, yet declaring its impending eruption has become a staple of political punditry. The current war in the Middle East is no different. The British media has debated how their country could get sucked into World War III if it allowed U.S. aircraft to use British air bases on their way to bomb Iran. In 2022 and 2023, figures including John Mearsheimer, Tucker Carlson, and Elon Musk warned that helping Ukraine fight Russia would set off a global conflagration. A recent poll conducted by Politico found that a majority of respondents in Britain, Canada, France, and the United States believed that World War III is more likely than not to happen within the next five years.

To understand the chaos in global politics, it is important to distinguish between different types of wars. This is not just semantics or academic exactitude, but a prerequisite for sober policy choices—not to mention keeping our sanity.

“World War III” is not a phrase to be casually tossed around, yet declaring its impending eruption has become a staple of political punditry. The current war in the Middle East is no different. The British media has debated how their country could get sucked into World War III if it allowed U.S. aircraft to use British air bases on their way to bomb Iran. In 2022 and 2023, figures including John Mearsheimer, Tucker Carlson, and Elon Musk warned that helping Ukraine fight Russia would set off a global conflagration. A recent poll conducted by Politico found that a majority of respondents in Britain, Canada, France, and the United States believed that World War III is more likely than not to happen within the next five years.

To understand the chaos in global politics, it is important to distinguish between different types of wars. This is not just semantics or academic exactitude, but a prerequisite for sober policy choices—not to mention keeping our sanity.

While Russia’s invasion of Ukraine and the U.S.-Israeli war against Iran are two serious conflicts with devastating consequences for the nations involved, they are both regional wars. That remains true even as Iran lashes out at its neighbors, which may or may not join the fight. A world war has considerably more profound effects on great power politics, stability, economic growth, and the international system compared to regional wars, limited wars, or various forms of hybrid and asymmetric warfare.

Yes, a spiraling war in the Middle East could have profound effects beyond the region. But for this or any other conflict to be called a world war, the following four criteria must be fulfilled.

First, a world war puts all or most of the great powers in the international system into direct confrontation with each other. Second, the military operations linked to the war are global in scope—or at least take place on two or more continents. Third, world wars are total wars, not limited wars, in the sense that the great powers mobilize a considerable amount of their military and other essential resources to fight. Fourth, the outcome of the war must have systemic effects, meaning a distinct shift in the balance of power between the great powers.

World War II obviously fulfills these four criteria. It involved all the great powers at the time, encompassed all inhabited continents, was a total war, and had major systemic effects. It catapulted the United States and Soviet Union to superpower status, while the former European great powers gradually lost their status and colonies. The war also led to the formation of the United Nations and Bretton Woods institutions, a completely novel way to organize the global system.

World War I was European at its core but eventually involved all the great powers at the time, including the Ottoman Empire and the United States. The war was global, with several fronts in Africa and the Asia-Pacific involving European colonial possessions. More than 2 million African and 1 million Indian colonial subjects fought or otherwise participated. The Allies—plus Japan, which declared war on the German Empire in 1914—took control of German colonial possessions from Southwest Africa to China to New Guinea and the Marshall Islands. World War I was definitely a total war. It had systemic effects, not least the dissolution of the Russian, German, Austro-Hungarian, and Ottoman empires.

Very few other wars throughout history qualify as world wars. Winston Churchill and others have posited that the Seven Years’ War (1756-1763) was the first true world war. Great Britain, France, Prussia, and other European major powers mainly fought on their continent, but the war also raged in North America (where it is called the French and Indian War), South Asia, and elsewhere. The war also enhanced Britain’s position as a global power.

Other observers categorize other large European conflicts as world wars, including the Nine Years’ War (1688-1697), War of the Spanish Succession (1701-1714), French Revolutionary Wars (1792-1802), and Napoleonic Wars (1803-1815) due to the extension of these conflicts to the main actors’ colonial possessions. Another candidate is the Mongolian conquest of most of the Eurasian continent in the 13th century. Still, even an expanded list of world wars is short.

The Cold War was global in scope, with several regional and proxy wars unfolding as a result of the U.S.-Soviet rivalry, but the two superpowers were never in direct military confrontation with each other, hence the moniker. Washington’s so-called war on terror was also global in scope, but it was a highly asymmetric war, not a conflict between major powers.

What about today’s candidates in the political conversation? Ukraine is certainly engaged in a total war against Russia; the stakes are nothing less than Ukraine’s survival as a nation. Moreover, the war has huge consequences for European security, U.S. strategy, and the international economy. North Korea has deployed soldiers to fight with Russia, and the outcome of the war will affect China’s reach into Europe via its quasi-vassal. But that does not make it a world war. Military operations only take place in Ukraine and Russia. There is no direct military confrontation between the United States and China, the two major powers in the current international system; consequently, the outcome of the Russia-Ukraine war will not have any systemic effects.

The Russia-Ukraine war remains regional, and in this regard, it resembles the Korean War (1950-1953). In Korea, however, one of the two superpowers at the time, the United States, was a main actor in the war. But even with the U.S. military fighting against the Chinese People’s Liberation Army directly, the Korean War did not have any systemic effects.

The current conflict in Iran and the Middle East is also a regional war—notwithstanding U.S. involvement, dramatic effects on energy prices, disruption of international air travel, and the large number of countries affected by Iranian missiles and drones. Indeed, Iran’s escalatory use of drones against its neighbors shows how easily a modern crisis can draw in other countries in the vicinity of a conflict zone.

Nevertheless, the conflict remains a regional crisis. It is not linked to Russia’s war in Ukraine, despite reports that Russia is feeding Iran with intelligence about U.S. military targets and Russia’s use of Iranian Shahed drones to attack Ukraine. Nor is China an important factor in the war, despite its close links to Iran, imports of crude oil from the region, and active diplomacy in the Middle East. It does not serve Beijing’s interests to intervene in the conflict. Even if it wanted to, it has neither the military foothold in the region nor the power projection capacity to join a war in the Middle East.

Bipolar international power structures—such as China and the United States today and the U.S.-Soviet rivalry during the Cold War—tend to be more stable and less conflict-prone than multipolar systems of three or more great powers. In addition, nuclear weapons have further reduced the risk of large-scale great-power war.

Today, the most likely scenario for war involving both superpowers involves a confrontation between the United States and China linked to the latter’s intent to take over Taiwan. There is, however, a possibility that a conflict between the two juggernauts could remain a limited war, depending on how Beijing and Washington manage the risk of escalation. It may remain a limited war if it were kept below the threshold of nuclear weapons (although there is an ongoing debate about limited nuclear war) and the fighting remained concentrated in the Western Pacific.

But the very fact that both China and the United States are contemplating the possibility of a limited war over Taiwan is in itself a risk of a greater conflict given the danger of vertical and horizontal escalation. European actors could be dragged into a U.S.-China conflict, and Russia may use a war in Asia as an opportunity to test European and U.S. resolve in Europe.

Given the economic and technological interconnections between modern societies, even a limited war in the Western Pacific or another regional war in Europe or the Middle East will have immense effects on countries, economies, and citizens far beyond the geographical center of a conflict. The consequences of another world war, on the other hand, are almost impossible to fathom.

War of any kind is better avoided, and escalation into a broader conflagration doubly so. To sharpen our analysis of policy choices—and keep our sanity in an increasingly chaotic world—we should avoid rhetorical escalation as well.