In our new era of great-power competition, it’s important to identity the competitors. But it has always been easier to speak about the great powers than to define them. Disagreement over great-power status, and especially over which power is the “greatest,” characterizes today’s system, as it did in times past. There is neither a commonly accepted definition of what constitutes a great power, nor any consensus over such basic questions as how many powers there are.
Nevertheless, we can distinguish the great powers by a set of common characteristics, which reveal that there are only four great powers that exist today—and they are not necessarily the ones you would expect.
Great powers, first of all, have a set of behaviors in common. They always expect to shape or at least be consulted on the main global issues of the day. They make their presence felt, and their absence creates a vacuum to be filled. Often, great powers will insist on their own absolute sovereignty but admit only the qualified sovereignty of lesser powers, especially if they are nearby. In extremis, they reserve the right to change regimes that threaten or displease them but are able to deny any such right with respect to themselves.
At times, the great powers will claim to be above international law. At other times, they will make a virtue of vindicating that law or claim to defend international norms. In other words, the great powers have the power to make the rules and to break them; they are never just rule-takers. They are the orderers, not the ordered.
What enables the great powers to behave this way are their superior capabilities compared to the middling and smaller states. The first such capability is resources. Does the state in question have the military capacity to impose its will or to resist that of others? There is no entirely satisfactory way of assessing military strength, but how much the state spends on its military and how effectively is a rough measure of its defense capabilities.
Deployable nuclear weapons are also an indispensable component of great-power status today. The guaranteed ability to deliver an atomic bomb and thus to deter a nuclear attack gives a state a special position in the world. This is why the great powers take on the immense burdens of planning, researching, maintaining, storing, training, and safeguarding associated with those weapons. Not all nuclear powers are great powers, but all great powers are nuclear.
Then there is the economy. Is the state strong enough to survive the financial headwinds of geopolitical competition and to sustain a substantial military effort? Usually, economic strength is measured by GDP, which covers everything produced within a state’s borders. The alternative metric of purchasing power parity takes into account how far a sum of money goes in the domestic economy. It privileges non-Western countries with lower standards of living and production costs.
Very important—and difficult to assess—is the question how national these resources are. Peacetime GDP, GDP in a conflictual situation, and wartime GDP are three very different things. Cut a state off from its markets, sources of credit, raw materials, and food supply through tariffs, sanctions, or a blockade, and its economy will soon take on a completely different aspect. This is where command of the global commons outside the jurisdiction of any one state—particularly the world’s sea lanes—is so important to determining great-power status, or at least the hierarchy among the great powers.
Economic power is thus important, but it is not conclusive in determining great-power status. The strongest militaries of the world measured in terms of capabilities and spending over the past 20 years are the United States, which comfortably leads the pack, and China, followed at some distance by the United Kingdom and Russia. The first three are also among the five or six largest economies in the world. Russia, which is economically weaker, makes the grade on the strength of its outsize nuclear arsenal—the largest in the world.
The second criterion of great-power status is reach. Is the state a global power or merely a regional power, and how willing and able is it to deploy force far from home? Does it have a recognized geographical sphere of influence? Can that state draw on a global network of bases? Does it control key transport nodes and chokepoints? Can its intelligence agencies provide top-quality information on most parts of the world, as well as for cyberspace and space? Does it have a large and sophisticated diplomatic service? Has it a large overseas aid budget?
Reach can be both geographic and virtual. A great power will have the capacity to make its presence felt well beyond its own region, but it will also have the capacity to influence or even coopt global institutions such as the United Nations, the markets, or other fora.
Today, reach is very unevenly distributed among powers. The United States stands out through its sprawling network of military bases. Britain does not enjoy remotely the same global position it once did, but it still maintains important sovereign bases worldwide, including Gibraltar, Cyprus, and the Falkland Islands; it also has a presence in places such as Duqm in Oman on the Indian Ocean. Russia claims a sphere of influence in its near-abroad, though it has recently lost ground in Africa and the Middle East. Russia also enjoys global reach in the fields of propaganda, disinformation, and disruptive digital activity.
China may yet become a major global military player, with a base in Djibouti and a large paramilitary presence protecting infrastructure projects across the world. Its real global reach, though, lies in its partial control of the world’s supply chains and critical minerals (such as lithium) needed to power the technological and green revolutions.
Mounted police officers lead the horse-drawn carriage procession of Britain’s King Charles III and Japan’s Emperor Naruhito as they make their way along The Mall in London on June 25, 2024, during a three-day state visit. Paul Ellis/AFP via Getty Images
