How Effective Would a Blockade be Against Iran?
Introduction The conflict between the U.S./Israel and Iran took another turn recently as President Trump announced the implementation of a blockade of Iranian ports to begin at 1000 hours Monday, April 12. Negotiations between the U.S. and Iran broke down this weekend with Iran claiming the U.S. was not trustworthy enough to make any deals with, and the U.S. setting 'Red Lines' that Iran was unwilling to agree to, most notably giving up its nuclear program and giving up on its control of the Hormuz Strait.
The Heckscher Framework Eli Heckscher studied Napoleon's Continental System and its effectiveness at punishing Great Britain through economic warfare. Out of his work came four dynamics (effectiveness/leakage, blowback, success probability, evasion networks) which help analyze the likelihood of the blockade succeeding. Below I look at what Heckscher's framework says about the blockade and its success, the cost to the U.S. in limiting whatever trade was happening between the two countries, and how quickly Iran begins to get around the blockade through the use of its almost 6000 km land border shared with a multitude of neighbors, some of whom would be more than happy to disobey the United States in this matter.
The Model
Our model predicts a 45% chance this blockade achieves its stated goals.
Sanctions Effectiveness (calculate_sanctions_effectiveness)
| Parameter | Description | Your Value |
|---|---|---|
num_sanctioners |
Number of nations actively enforcing the blockade | 6 (US, Kuwait, Qatar, Saudi Arabia, Bahrain, and Israel) |
target_gdp |
Iran's GDP in billions USD | 475.252 |
target_trade_openness |
Iran's (exports + imports) / GDP ratio | .100 (actually .084 but that level of granularity is not available at the moment) |
enforcement_capacity |
How effectively the blockade is monitored (0-1) | .5 |
border_length_km |
Iran's total land border length in km | 8709 km (land and coastline) |
num_willing_neutrals |
Nations willing to trade with Iran despite blockade | 50 |
corruption_level |
Corruption in Iran and enforcing nations (0-1) | .5 |
months_active |
How long the blockade has been in effect | 0 |
target_is_autarkic |
Is Iran's economy self-sufficient? (true/false) | false |
| For the nations participating in the sanctions I chose the six nations targeted the most by Iran in the latest conflict. Other than the United States, we will likely not see any of the other nations committing naval forces to enforce the blockade. However, their providing moral and diplomatic support may help. A high number of nations willing to trade with Iran was chosen to reflect the general dissatisfaction with the U.S. and Israeli unilateral actions. Enough countries have found the conflict immoral that 25% of the world's nations willing to defy the blockade seems reasonable. |
The U.S. Navy is more than capable of enforcing at better than .5. However, less than half of the Iranian border is coastline. Borders with Iraq, Turkey, Azerbaijan, Afghanistan, Pakistan...the Iranian land border is impossible to close. Will Iran's allies step up and help soften the economic blow a blockade such as this may cause?
**Blowback to the United States
| Parameter | Description | .08 Effectiveness |
|---|---|---|
sanctioner_gdp |
US GDP in billions USD | 28750.956 |
bilateral_trade_volume |
Pre-blockade US-Iran trade volume (millions) | 838.4 |
effectiveness |
Result from the effectiveness calculation above | .084 |
sanctioner_trade_openness |
US (exports + imports) / GDP ratio | .1809 |
trade_loss |
Effect of blockade on US trade | ($80 million) |
| This function explores the potential hurt the United States might suffer to its own economy by blockading Iran. Although $80 million is a drop in the bucket, it still means this conflict will cost even more money beyond the operational costs involved to say nothing of the loss of soft power. Will the gain in coercive power be enough to make up for the economic and diplomatic losses. |
**Success Probability
| Parameter | Description | Your Value |
|---|---|---|
num_sanctioners |
Same as above | 6 |
target_gdp |
Same as above | 474.252 |
target_regime_type |
"democracy", "authoritarian", or "totalitarian" | authoritarian |
goal_type |
"symbolic", "policy_change", "deter_war", or "regime_change" | policy change (give up nuclear programme, and give up control of the Strait of Hormuz) |
duration_months |
Expected duration of the blockade | 2 |
financial_sanctions |
Are financial sanctions included? (true/false) | false--although there are currently financial sanctions, these sanctions were already in place before the current conflict. |
I have estimated any blockade lasting no more than two months. The cost of maintaining the blockade in addition to the instability present in the Persian Gulf lends momentum to this action not lasting very long.
Evasion Network Growth
| Parameter | Description | Your Value |
|---|---|---|
months_active |
Same as above | 0 |
border_length_km |
Same as above | 8,709 |
num_willing_neutrals |
Same as above | 50 |
corruption_level |
Same as above | .55 |
target_gdp |
Same as above | $475.252 bn |
enforcement_capacity |
Same as above | .5 |
| Evasion Networks Present | 0* | |
| This number will not remain zero for long. In fact, it would not be surprising if land routes traveling from China through Pakistan are already in the early stages of implementation. The presence of corruption in Iran (another estimate by the author) would also mean a robust black market presence fairly quickly. If these networks proliferate at numerous points on the Iranian border, will the U.S. feel compelled to deploy ground troops to stop the most egregious blockade busting land networks? |
A 45% chance of the blockade succeeding asks the question of what options did the U.S. feel it had that it rejected. Heckscher writes of blockades as weapons of attrition. We can assume, the option to resume bombing Iran was discarded. Is this a strategy intended to show the world we are doing something or a reaction to negotiations not going well? Either way, it is another way for the United States to flex its might. Can the U.S. flex this power long enough for this weapon of choice to work? We do not know, Pres. Trump's strategic impulses are not conducive to long-term thinking, but in order for a blockade to work the blockading side needs to button up access to the country, patience to let the effects build up over time, and the diplomatic might to dissuade other nations from skirting the blockade.
General Sources: https://www.nytimes.com/live/2026/04/12/world/iran-war-trump-talks-pakistan/d9a73c30-a7f7-52b2-bc7d-aa522a7bb824?smid=url-share
2024 Economic Data Sources: GDP https://data.worldbank.org/indicator/NY.GDP.MKTP.CD?locations=US, https://data.worldbank.org/indicator/NY.GDP.MKTP.CD?locations=IR US-Iran Trade https://ustr.gov/countries-regions/south-central-asia/iran Import/Exports Totals https://www.bea.gov/news/2025/us-international-trade-goods-and-services-december-and-annual-2024, https://oec.world/en/profile/country/irn Iranian Coastline https://en.wikipedia.org/wiki/Geography_of_Iran
This analysis uses the Heckscher economic warfare model from the Balance of Power theory engine. Explore the full /portal to see how the model works.