Monday, 7 September 2026
On Saturday the war with Iran changed what it was aimed at. The United States struck three Iranian crude tankers: the Downy off Kharg Island, the Stark 1 near Jask, and the Kylo in the Gulf of Oman, which was sunk after its crew was told to get off. Central Command called the three ships part of a shadow network that moves Iranian oil to buyers who do not ask questions and returns the money to the Revolutionary Guard. The strikes answered ballistic missiles that Iran had fired at an American carrier and a destroyer earlier in the week; both ships evaded them, and nobody on the American side was hurt. The commander’s arithmetic was plain: two of our ships shot at, three of your tankers gone. By Sunday Tehran had promised crushing retaliation, and the Strait of Hormuz, which carries roughly a fifth of the world’s oil, looked more like a front than a shipping lane.
That was day 191 of an open war, so Saturday was not a beginning, and it is a mistake to read it as one. What changed was the target. Warships had been shooting at warships; the ceasefire agreed in June was already dead. Saturday was the first time Washington went after the money, and that is a different kind of move, because oil is the one thing Iran cannot defend at sea. It can only make the other side pay somewhere else.
It is tempting to blame the escalation on bad diplomacy or hot rhetoric. I read the map through a different book, and it makes the week look less like a failure of statesmen and more like a machine doing what it was built to do.
The book that maps the tragedy
John Mearsheimer published The Tragedy of Great Power Politics in 2001 and updated it in 2014, and it is still the clearest statement of what he calls offensive realism. The argument rests on five assumptions, and none of them is exotic. There is no authority above states to protect them. Every state has some capacity to hurt its neighbors. No state can be certain what another intends, now or in ten years. Survival comes before every other goal. And states are rational enough to plan for the worst. Put those together and fear does the rest. A state that cannot know its rival’s intentions, and cannot call for help when it guesses wrong, will want as much power as it can get, and the safest amount is enough that nobody in its region can threaten it. The ideal is regional hegemony. Global hegemony is off the table, because oceans stop armies. So the strongest state in each region tries to dominate it, and works to keep every other region from producing a rival that could do the same.
The book is about great powers, and most people who cite it skip that. Mearsheimer counts very few of them: the United States, China, Russia. Iran is not one. So applying the theory to Tehran is a transfer rather than a reading, and I will make the transfer in the open. The logic of fear and uncertainty holds for any state that wants to run its own neighborhood and finds a stronger power standing in it. What does not transfer is the claim that the outcome was forced, and I will come back to that.
The zero-sum game of the Strait
The United States, in this theory, is the only regional hegemon on earth. Nobody in the Western Hemisphere can touch it. Its interest elsewhere is narrower than people assume: not to run Europe, Northeast Asia, or the Persian Gulf, but to make sure nobody else runs them, and Mearsheimer’s name for how it should do that is offshore balancing. Stay over the horizon and let local states carry the load; come in only when a would-be hegemon is about to win. The Persian Gulf is on his list for one reason, oil, and that is why the Strait matters to Washington beyond the price at the pump. A power that can close Hormuz is a power that dominates the region, and letting missiles at your warships go unanswered tells everyone watching that you are no longer the one who decides.
Iran, in the same theory, is the state that wants the region and finds an outside power standing in it. From Tehran’s side the American presence is not a policy to negotiate with but a permanent fact to be removed, because as long as it is there Iran’s security depends on another government’s mood. Every tanker seized and every missile fired is a way of raising the price of staying until Washington decides the Gulf is not worth it. That is not madness. In the book’s terms it is the only rational move open to a state that cannot win a straight fight.
Why nobody can back down
This is the part the word tragedy is for. Grant that both governments would rather not be doing this. It changes nothing, because neither can trust the other’s restraint. If the United States pulls back, it cannot know that Iran will not fill the space. If Iran stops, it cannot know that the sanctions will not tighten anyway. Each side’s defensive move is read by the other as an offensive one, and each side is right to read it that way, since it cannot see intentions and has to plan against capabilities. Political scientists call this the security dilemma. The book’s contribution is to insist that it is not a misunderstanding waiting to be cleared up. It is the structure.
Saturday’s strikes were an attempt to restore deterrence by demonstrating that the United States can hit what Iran cannot protect. Tehran cannot let that stand without looking weak, and in its logic looking weak invites the next blow. So it will answer. Then Washington will answer that. Nothing in the sequence requires anyone to be stupid.
Where the book and its author part company
Now the correction, because the book’s author would not sign the line that this is a war of structure rather than choice, and I do not think it is honest to hand you his book without his view. Mearsheimer has spent twenty years arguing that America’s wars in the Middle East are wars of choice, produced by a grand strategy he calls liberal hegemony, and that the structurally sound policy for the Gulf is to stay offshore and let Iran be balanced by its neighbors. On his account the trap is real, and the United States walked into it. The theory explains why nobody can climb out this week. It does not say the hole had to be dug.
So which is it, structure or choice? Both, and that is the tragedy in the title. Structure explains the spiral. Choice explains the entry. A government gets to pick the moment it stops being able to choose.
What to watch next
Tehran’s promised retaliation is the obvious item, and the book tells you where to look for it: not only at warships but at the things American power in the Gulf exists to protect. Tankers, terminals, the flows themselves. Iran’s cheapest move is to make the Strait unsafe for everyone rather than to fight the Navy for it.
Watch the oil market, but watch the neighbors harder. Saudi Arabia and the Emirates have two options in the book’s vocabulary. They can pass the buck, which means letting the United States carry the whole cost of checking Iran while they stay out of the line of fire, and Mearsheimer’s own prediction is that states pass the buck whenever a distant balancer is willing to catch it. Or they can balance, which means arming and joining in. Which one they choose this week tells you whether they think Washington is staying.
The tragedy of great power politics, in the book’s own sense, is that the search for security produces the insecurity it was meant to prevent. The map of the Strait is being redrawn this week, and not by diplomats.
This week’s book: John Mearsheimer, The Tragedy of Great Power Politics (W. W. Norton, 2001; updated edition, 2014).
Sources: U.S. Central Command statement and Adm. Brad Cooper’s remarks on the strikes (5 September 2026); NBC News and ABC News, US strikes three Iranian tankers after missile attacks on Navy ships (5 September); Al Jazeera, the shadow-network justification (5 September); CNN, Tehran’s retaliation vow (6 September); Associated Press and NPR, missile attacks on Navy ships (5 September); CNBC, oil market reaction (7 September). Book: John Mearsheimer, The Tragedy of Great Power Politics (2001; updated 2014); John Mearsheimer and Stephen Walt, The Case for Offshore Balancing, Foreign Affairs (2016); John Mearsheimer, The Great Delusion (2018).