The LBJ Hormuz Working Group conducted a military campaign analysis of an Iranian attempt to close the Strait of Hormuz. Our ultimate goal in conducting this analysis was to gauge the likelihood that Iran could successfully interrupt traffic in the Strait for a prolonged period of time given their current military arsenal.

In this section:

  • Key Assumptions 
  • Chosen Weapons for Analysis 
  • Measure of Merit 
  • Results 
  • Conclusion 

Key Assumptions

  • The Group considered the impacts and implications of a short-term (hours or days) disruption of traffic but believed that only a long-term disruption would substantially impact the global economy 
  • The Group did not analyze terrorist attacks (e.g., uncoordinated IRGC suicide attacks) as viable tools in a strategy to sustain a long-term disruption of traffic in the Strait 
  • Although Iran does possess limited air and conventional naval fleets, we assumed that Iran would not choose to use these assets in any campaign because of U.S. naval and air superiority 
  • The most effective way to materially disrupt oil flows through the Strait would be to physically damage large oil tankers, or VLCCs. With Iran's limited military assets, our Group assumed that Iran would target only these large tankers 

Chosen Weapons for Analysis

After analyzing the Iranian arsenal, the Hormuz Working Group focused on three weapons that would most likely be employed if Iran attempted to disrupt tanker traffic in the Strait of Hormuz. These weapons are small suicide boats, anti-ship cruise missiles, and naval mines. We selected these weapons based on their historical use, potential damage capability when facing a VLCC oil tanker, and the propensity of Iran to use those assets to achieve their goal.

Measure of Merit

The LBJ Hormuz Working Group developed a model for each of the three weapons included in the analysis. Taking into account a number of factors (e.g., historical use by Iran, sophistication of weapons, weather conditions), each model estimated:

  • Expected number of VLCC "hits" 
  • Expected number of sunk or considered total hull loss (CTL) VLCCs 
  • Total amount of barrels of oil disrupted in the Strait (about two million barrels for each VLCC) 

Results

Below are the results for each of the weapons in Iran's best case scenario:

  • Small Boats - Iran could expect to significantly damage 33 percent of the tanker traffic on a given day, or about seven VLCC tankers. Most of the tankers could be repaired and returned to the tanker fleet after a period of time. This damage estimate compensates for any abnormalities in the data calibration and awards Iran the benefit of the doubt in every case including doubling the estimate for the limiting variable of the intercept. 
  • Missiles - Iran could expect to significantly damage about 25 percent of the tanker traffic on a given day, or about five VLCC tankers. Again, this estimate favors Iran both in the number of missiles fired at the tankers and the estimates used for the steps of the kill chain. 
  • Mines - If Iran lays a minefield only six or seven tankers would be affected during the entire time that the minefield is active - even assuming tankers continue to attempt to complete their routes as normal. 

Conclusion

Iran certainly possesses the capability to damage a VLCC in the Strait of Hormuz. Assuming that Iran successfully applies these capabilities (using a conservative estimate), the percent of significantly damaged tankers is noteworthy, but should not elicit panic. Furthermore, in the rare case that Iran attacks a second time the next day, it is unlikely Iran would be as successful because the U.S. and others would almost certainly employ defensive measures almost instantaneously.