It’s Time to Talk About a New World War
The U.S. is approaching the six-month mark since it launched its war against Iran alongside Israel. The conflict has been through starts and stops, with ceasefires signed and broken, and escalation threatened and then avoided. What started as a campaign that was supposed to quickly decapacitate Iran’s leadership and bring about victory in weeks is no closer to a resolution than it was months ago. Meanwhile, the Ukraine war continues to drag on and will soon reach its four-and-a-half year mark.
In April, I claimed in an op-ed for The New York Times that because these two conflicts were increasingly interacting with each other, we should understand them as comprising a new world war. Events since then have left me even more convinced that this is the case.
A world war takes place when at least two separate international conflicts become interconnected, with common belligerents. For many observers, myself included, the archetypal example is World War II, which was arguably the only conflict in human history that engulfed nearly the entire globe. But that does not mean a war must be as intense and deadly as World War II to be considered a world war.
World wars, as I define them above, have actually been quite common in human history. According to Winston Churchill, the Seven Years’ War that raged in Europe and North America in the mid-1700s was “a world war—the first in history.” But one could argue that world wars began much sooner, such as the War of Spanish Succession in the early 1700s. The American Revolution was itself fought across the globe, as were the Napoleonic Wars.
The strategist and scholar Eliot Cohen has argued that the Cold War was a world war. Those decades certainly involved violent conflicts across much of what we now refer to as the Global South, but it doesn’t meet my definition of “world war,” mainly due to the lack of simultaneity and integration in the fighting.
The point is that world wars are quite common, and I see the wars in Ukraine and Iran as together constituting the latest one. For starters, the theater of fighting in the Iran war has widened to include fighting against Iranian-backed groups in Lebanon and Yemen, along with Iranian strikes against various Gulf neighbors aligned with the United States. It is no longer a one-off and isolated conflict, like the 2025 Twelve-Day War, but has instead become a regional conflict. Similarly, while the war in Ukraine has not engulfed all of Europe, it has long been a multilateral conflict drawing in the active involvement of numerous states—from multiple continents—backing one of the warring parties.
As more nations have gotten involved, the wars have increasingly converged. Russia is not only providing weapons to help resupply Iran, but has also been providing intelligence and targeting information to help Tehran strike U.S. targets. Even Secretary of Defense Pete Hegseth acknowledged that Russia, as well as China, are “enabling some of the things Iran is doing.” As Bradley Bowman and Cameron McMillan noted in an op-ed this week for The Washington Post, “A significant reason for Iran’s resilience, lethality and leverage is the growing support Tehran is receiving from China and Russia.”
So many countries have piled in to both wars that it is becoming difficult to determine where the theater of one conflict ends and the other begins.
Moscow has good reasons for wanting to merge the two conflicts. It has a strong and longstanding alliance with Iran, and Putin sees the war in Ukraine as but part of a global struggle against the West. The U.S. has long supported Ukraine with weapons and targeting assistance against Russia, so Putin views his support of Iran as more than justified.
Iran, in turn, is continuing to supply military equipment to Russia, as it has done since Putin launched his full-scale invasion of Ukraine in 2022. Indeed, that led Kyiv in late July to attack an Iranian ship in the Caspian Sea, and Ukraine was already assisting Gulf States with targeting and defending themselves against Iranian drones. China has also furthered its support for Iran, though not yet at the same level as Russia.
Other nations are playing a key role in one of the wars, but not the other. For instance, while North Korea has so far avoided direct assistance to Iran, it has been supplying troops and materiel to Russia since 2024, and there are reports that it could send thousands of additional troops to fight in Ukraine this fall. But the assistance that North Korea provides gives Russia the bandwidth to maintain its support to Iran.
In short, so many countries have piled in to both wars that it is becoming difficult to determine where the theater of one conflict ends and the other begins.
Additionally, and perhaps more concerningly, this has created conditions that place the wars on the precipice of expanding further. With the trans-Atlantic alliance in dispute over the war in Iran, Russia has become more assertive in its drone incursions against European nations, and Western intelligence agencies have warned that Russia could be planning a larger attack against Europe. The Financial Times reported recently that Iran is making direct threats to launch missiles at European nations if the United States attempts to escalate strikes against Iran. And the United States recently redeployed its only aircraft carrier in the Asia-Pacific to the Middle East. This underscores how the war is opening space for China to potentially take action against Taiwan. Indeed, Beijing has increased “law enforcement patrols” in the waters east of the disputed island.
Some would assert that these conditions do not qualify as a world war, since that would require direct combat between the military personnel of the major powers. But the reality is that in today’s world, with warfare increasingly being carried out through exchanges of missiles and other projectiles, the nature of combat has changed. If a major power is supplying missiles to a warring party, equipping the launchers, having its personnel train and assist local personnel in how to use them, and then providing targeting information on which targets to hit, well, the only thing the major power has not done is pull the trigger.
To be clear, the current world war will almost certainly not reach the level of violence seen during World War I and World War II, even though the destruction wrought is still notable. In that sense, it is a low-level world war. But that doesn’t mean it lacks the potential to remake the world order.
Paul Poast is an associate professor in the Department of Political Science at the University of Chicago and a nonresident fellow at the Chicago Council on Global Affairs.