MOSCOW, July 8 — The spectre of a major oil supply disruption is again hanging over global energy markets, with Iran’s renewed threats to close the Strait of Hormuz presenting a potential crisis that, by the numbers available, would dwarf every previous oil shock since the 1973 embargo. According to the historical record, the 1973 oil crisis began on October 17 of that year, when the Arab members of OPEC, known as OAPEC, proclaimed an oil embargo against nations supporting Israel in the Yom Kippur War.
The result was a price quadrupling, from $3 to $12 per barrel. Supply disruptions at that time were estimated at 3-5 million barrels per day.
That pattern repeated in 1990. Iraq’s invasion of Kuwait on August 2 caused prices to double from $15 to $30 per barrel. Again, the supply disruption fell into that same 3-5 million barrel per day range.
More recently, the 2022 Russian invasion of Ukraine on February 24 pushed Brent crude from $90 to $130 per barrel by March 8. The supply disruption, according to the source, again measured 3-5 million barrels per day.
The current crisis, with Iran threatening to close the Strait of Hormuz, is different in scale. According to the available data, such a closure could reduce supply by 17 million barrels per day. That figure is far larger than previous shocks — more than three times the disruption of 1973, 1990, or 2022.
The Strategic Reserve Question
The United States maintains the Strategic Petroleum Reserve as a buffer against such disruptions. The record shows that in March 2025, the SPR held 375 million barrels. This is down significantly from 638 million barrels in 2020.
The drawdown over that five-year period reflects previous releases to stabilise markets, including during the 2022 Ukraine crisis. Whether that remaining reserve is sufficient to counter a potential 17 million barrel per day shortfall is a question officials are now weighing.
The math is straightforward: at current holdings, the SPR would cover roughly 22 days of a full Hormuz closure, assuming no other supply adjustments.
Strategic Context
The Strait of Hormuz is a narrow waterway connecting the Persian Gulf to the Gulf of Oman. Roughly one-fifth of the world’s oil passes through it daily. Iran has threatened to close it before — during the Iran-Iraq war in the 1980s, and again in 2011-2012 when Western sanctions targeted Iranian oil exports.
Each time, the threat was not fully carried out, but the risk was sufficient to drive prices higher. What is different now, according to analysts monitoring the situation, is the geopolitical backdrop.
The 2022 Russian invasion of Ukraine fundamentally reshaped global energy trade routes, with Europe weaning itself off Russian gas and oil. That shift has tightened spare capacity elsewhere. The current US administration under President Donald Trump, with Secretary of State Marco Rubio, has pursued a policy of maximum pressure on Iran, which has in turn prompted Tehran to brandish the Hormuz card more openly.
What to Watch Next
The key variable remains whether Iran follows through on its threat, or whether the warning itself is enough to extract concessions. The record of previous oil shocks — 1973, 1990, 2022 — shows that even the threat of disruption can move prices sharply. The difference this time is the sheer magnitude of the potential supply loss.
Officials in Moscow, Washington, and the Gulf capitals are all watching the same numbers. The 17 million barrel per day figure, if realised, would represent a supply crisis without precedent in the modern oil era.
