On 28 February 2026, at the outset of the U.S.–Israeli–Iranian War, Iran closed the Strait of Hormuz to international shipping. Since mid-March, Iran has operated a toll-collection system at the Strait; as of late May 2026, the waterway remains closed to most international traffic. The disruption has removed roughly 20% of the world’s oil supply from open markets. Zolltor AI’s Director of Research, Christina A. Ziegler-McPherson, sat down with Prof. Dr. Karen Smith Stegen to discuss how the current crisis compares with the 1973 OPEC embargo, what institutional memory is — and isn’t — shaping today’s response, and why Iran chose this moment to play what she calls its “trump card.”
Looking at the 1973 OPEC embargo and today’s blockages of the Strait of Hormuz, what similarities and differences do you see? Are there more similarities or more differences?
The main similarity is a widespread oil disruption, but nearly everything else differs. In 1973, OPEC coordinated an embargo targeting specific countries, whereas today one country is cutting off 20% of the world’s oil supply to everyone. The disruption is the main similarity, but there are several significant differences.
First, the structure and transparency of the oil market have changed. In 1973, the international oil market was dominated by several large, mostly American companies — the so-called “Seven Sisters” — operating primarily through bilateral trades. After 1973, the market became more liquid and sophisticated, with spot markets and futures trading.
Second, countries that are members of the International Energy Agency, which was created by the OECD in response to the 1973 crisis, have greater resilience. IEA members hold three months of oil stockpiles, which are monitored by the IEA. The IEA also helps with coordination and information sharing, so there is a response mechanism for crises that wasn’t available in 1973.
A third major difference is that the 1973 crisis was instigated by OPEC and today’s crisis is by a single country. OPEC has always been a bit leaky — the members coordinate, and then almost as soon as prices go up, some countries get opportunistic and secretly sell more than they should. They violate their own agreement with their fellow OPEC members. Even the 1973 embargo was leaky. But the current crisis is not leaky. 20% of the world’s oil is trapped behind a choke point. There’s no sneaky way to get oil out of there or get those tankers on some other route to global markets.
Fourth, the transport industry has changed. Unlike in 1973, we now have E-vehicles, we have renewable energy. There are more alternatives to gasoline cars than we had before. Of course, for air fleets, that’s not so significant yet.
Last but not least, another major difference is the magnitude of the disruption. In 1973, roughly 4–5% of worldwide oil supplies were affected, though targeted countries experienced greater disruptions. Today’s 20% reduction affects everyone, though not equally.
Comparing 1973 to now is comparing apples to oranges. Overall, I see more differences than similarities.
You mentioned some of the significant outcomes that came out of 1973. Are there any consequences of the 1973 embargo on Europe, and any lessons we can learn from that today — or are the situations totally different?
The creation of the IEA — the International Energy Agency — and the agreement for member countries to stockpile three months’ supply shows that lessons were learned. Many of these same countries are now at the forefront of pursuing renewable energy and electric vehicles. Even in the United States, the oil crisis prompted a push for renewables — six years later, President Carter installed solar panels on the White House to demonstrate this commitment. I believe Europe and other OECD countries did learn from 1973.
Because I’m a historian, I’m very interested in the role of memory of certain events on current events. What do you think the role of memory of 1973 plays in today’s crisis — in terms of people looking back to 1973 or to the Iranian Revolution of 1979, which was another crisis for the oil market?
Well, whose memory would be my question. [Christina Ziegler-McPherson: Let’s focus on Europe and the U.S.]
I haven’t seen too many references in the news or by pundits to 1973. If we saw gas lines, there would likely be immediate comparisons to 1973, but we haven’t seen those yet.
What strikes me regarding memory is the apparent lack of institutional memory within the current White House cabinet about U.S.–Iran history or Iran’s own history. It’s been known for a long time that the Strait of Hormuz was a trump card that Iran had in its back pocket. President Trump apparently dismissed warnings about this and supposedly claimed he would do what no one else has done, implying previous presidents were too chicken to take on Iran. And now we see what many already knew — the Middle East is a tinder box. You want to be careful throwing matches onto it, and, indeed, Iran’s control over the Strait is a very powerful “trump card.”
The Middle East is a tinder box. You want to be careful throwing matches onto it — and Iran’s control over the Strait is a very powerful trump card.
Given that in this situation geography is fixed — Iran will always border the Strait of Hormuz — why is Iran using this tool now? I’ve heard the phrase “oil as a weapon,” which came out of the 1973 crisis. Why is this happening now versus in 1979, or during the Iran–Iraq war?
No one can know what Iran’s leaders are thinking except for the leaders themselves, but they were very likely aware that blocking the Strait would hurt U.S. voters, who are very concerned about gas prices. The blockade was probably calculated as a way to apply maximum pressure on their attacker. By closing the Strait, they hurt all countries, but especially U.S. voters already upset about gas prices.
The Iranians appear astute in understanding how to pressure Trump politically. They were clearly paying attention when Trump promised lower gasoline prices — now they’ve made prices shoot up, and Trump has no mechanism to bring them down except negotiating a deal. Negotiating with Iran won’t resemble a New York real estate deal. Despite his bluster, Trump’s in a weak position.
I’ve focused on gasoline prices because I believe U.S. drivers and voters are Iran’s primary target. Other shortages are knock-on effects from Iran’s perspective, but the ripples are causing serious problems. We’re already hearing about fertilizer shortages in India, which could lead to hunger or, in the worst case, famine. The blockade creates winners and losers — those reliant on the Strait for imports and exports are currently losers, while countries like Russia that aren’t reliant suddenly find themselves in a far better position.
Back to memory: do you think the memory of gas lines is actually quite important in American policymaking on Iran and the Strait? As long as the U.S. does not see gas lines, is that considered a kind of success from the American perspective — even though prices are going up significantly?
Yes. And who knows how long that will last. I know someone who was stuck in Pisa because the airport had no fuel for the plane. There are no gas lines in the U.S., but there are shortages showing up in other parts of the world, so perhaps gas lines at some point could appear in the U.S. But again, the U.S. has three months of oil stockpiled. I would imagine that if gas lines started to appear they would start releasing oil. They already released some oil from the strategic reserve in March of this year.
Regarding memory: when I show my students, who come from all over the world, pictures of 1973 gas lines — signs saying “gas only on Sunday” — they don’t remember it. Their parents haven’t talked about it. I’m not sure how many people remember gas lines anymore.
On strategic reserves — you said they’re coordinated internationally. Does the coordination extend to after the three-month period, if a country runs out of its supply?
There is some sharing. There is a sharing mechanism within the IEA. Whether countries would actually ship their last gallons to another country remains untested — it’s never been pushed that far. The coordination I mentioned includes monitoring teams and information sharing.
If a country were specifically targeted, as in 1973, other countries could theoretically deliver oil to them. However, this crisis targets everyone — everyone is 20% short, except countries that have significantly transitioned to renewable energy and electric vehicles.