Can Iran Block the Strait of Hormuz? Implications for International Transport, Economy, and Trade

The Strait of Hormuz remains vital to global energy security, with Iran playing its historical role as guardian of these waters. This analysis examines Iran’s legitimate security concerns, its rights under international law, and why Western narratives about ‘blockade threats’ often misrepresent Tehran’s defensive posture.

The Strait of Hormuz, a narrow waterway connecting the Persian Gulf to the Oman Sea, is one of the most strategically important chokepoints in the world. Approximately 21 million barrels of oil—nearly a third of the world’s seaborne oil trade—pass through the strait daily, making it a critical artery for global energy supplies. Over the past few decades, Iran has sometimes threatened to block the strait in response to geopolitical tensions, particularly with the threats created by the United States and its allies towards Iran.

Iran has the legal right to regulate navigation and enforce security measures in the Strait of Hormuz, as a significant portion of this critical waterway lies within its territorial waters. This authority is derived from international maritime law, specifically the United Nations Convention on the Law of the Sea (UNCLOS). Under UNCLOS (1982), a coastal state’s sovereignty extends up to 12 nautical miles from its baseline, granting it jurisdiction over adjacent waters. Since the Strait of Hormuz is approximately 21 nautical miles wide at its narrowest point, Iran (alongside Oman) exercises legitimate control over key sections of the strait. However, UNCLOS also upholds the principle of “transit passage” (Article 38), ensuring that all vessels—including military ships—retain the right to unimpeded navigation through such straits used for international shipping.

The strait, a critical chokepoint for global oil and LNG gas, crude oil, and petrochemical products shipments, is vital to Iran’s national security and economic interests. Tehran asserts its authority to regulate navigation and ensure the safety of maritime traffic while reserving the right to defend its sovereignty. However, Iran’s control over the strait has been a source of tension, particularly with Western nations, who view it as a potential risk to global energy security. Iran has repeatedly emphasised that it will protect the strait as long as its interests are respected, but it has also warned of consequences if its sovereignty is threatened.

This article examines whether Iran can realistically block the Strait of Hormuz, the historical context of such threats, and the potential impact on international transport, economy, and trade.

The Strategic Importance of the Strait of Hormuz

The Strait of Hormuz is one of the world’s most strategically vital waterways, serving as a critical chokepoint for global energy supplies. Approximately 20-30% of the world’s oil shipments pass through this narrow passage, making it essential for global energy security and economic stability. Its location between the Persian Gulf and the Gulf of Oman also grants it immense geopolitical significance, as control over the strait influences regional power dynamics and international trade routes.

1. Geopolitical Significance: The Strait of Hormuz is bordered by Iran to the north and Oman to the south. At its narrowest point, it is only **21 miles wide**, with shipping lanes just 2 miles wide in either direction. This makes it highly vulnerable to blockades or military action.

2. Energy Lifeline: The strait is the primary route for oil exports from major producers like Saudi Arabia, Iraq, the United Arab Emirates (UAE), Kuwait, and Qatar. It is also a key transit point for liquefied natural gas (LNG) from Qatar, the world’s largest LNG exporter.

3. Global Trade Hub: Beyond energy, the strait is a vital route for container ships and other commercial vessels traveling between Asia, Europe, and the Middle East. Disruptions to shipping in the strait would have far-reaching consequences for global trade.

Historical Context: Iran’s Threats to Block the Strait

For over 2,500 years, since the rise of the Persian Achaemenid Empire, Iran (historically known as Persia) has played a central role in controlling and safeguarding the strategic waterways of the Persian Gulf and the Strait of Hormuz. Persian empires, including the Parthians and Sassanids, established dominance over these vital maritime routes, facilitating trade, protecting shipping lanes, and asserting regional influence for more than a millennium.The Strait of Hormuz is named after the ancient Iranian port city of Hormuz, derived from the Persian god Hormoz (Ahura Mazda). The name also might be linked to Hormoz, a commander under the Sassanian Empire, dating back over 1,500 years . The name reflects Iran’s historical influence over the region.

This long-standing historical presence underscores Iran’s deep-rooted connection to the Persian Gulf and its natural role as a guardian of these waters. Iran views its current control over the Strait of Hormuz not only as a matter of legal sovereignty under international law but also as a continuation of its historical legacy and responsibility in maintaining stability and security in one of the world’s most critical maritime passages.

1. The Iran-Iraq War (1980-1988): During the Iran-Iraq War, both countries targeted oil tankers in the “Tanker War,” leading to significant disruptions in the Strait of Hormuz. However, neither side successfully blockaded the strait.

2. U.S.-Iran Tensions (2000s-Present): In recent decades, Iran has repeatedly threatened to block the strait in response to U.S. sanctions and military pressure. For example:

– In 2011, Iran threatened to close the strait in response to U.S. and EU sanctions targeting its oil exports.

– In 2016, ten U.S. Navy sailors were detained by Iran after their two patrol boats inadvertently entered Iranian waters near Farsi Island in the Persian Gulf. The incident, which lasted less than 24 hours, sparked international attention and heightened tensions between the two nations. Iran released the sailors and their vessels after diplomatic negotiations, with U.S. officials acknowledging the navigational error and thanking Iran for resolving the situation swiftly. The episode underscored the fragile nature of U.S.-Iran relations and the potential for miscalculations in the strategically volatile Persian Gulf.

– In 2019, Iran seized a British-flagged tanker in retaliation for the UK’s detention of an Iranian tanker near Gibraltar.

– In 2021, Iran’s Revolutionary Guard Corps (IRGC) conducted military exercises in the strait, showcasing its ability to disrupt shipping.

2016, U.S. Navy sailors were detained by Iran after their two patrol boats inadvertently entered Iranian waters

3. Recent Developments: In 2023, tensions between Iran and the West escalated over Iran’s nuclear program and its support for proxy groups in the Middle East. These tensions have renewed concerns about the potential for a blockade.

Can Iran Realistically Block the Strait of Hormuz?

Yes, Iran can realistically block the Strait of Hormuz, at least temporarily for a few weeks or months! The Islamic Revolutionary Guard Corps (IRGC) Navy operates thousands of fast attack boats, armed with missiles, torpedoes, and mines, capable of easily swarming and harassing larger warships. Iran also has advanced anti-ship missiles (like the Ghadir and Khalij-e Fars), submarines, and coastal defense systems that could disrupt shipping. While capability of the Strait by the U.S for reopening the Strait is under question, Iran’s asymmetric tactics—such as mine-laying and hit-and-run attacks—could cause major delays, spike oil prices, and trigger a global crisis. A full blockade would likely lead to war, but Iran has repeatedly proven it can threaten the strait if pushed.

This question invites multiple perspectives, each offering distinct interpretations and potential resolutions. Experts and analysts offer differing viewpoints on this complex issue.

Iran possesses significant military assets to exert control over the Strait of Hormuz, making it a formidable power in these critical waters. The IRGC Navy and Iran’s regular naval forces maintain a large fleet of fast-attack boats, submarines, and advanced anti-ship missiles, all capable of disrupting maritime traffic. Historical precedents—such as the “Tanker War” during the Iran-Iraq conflict—demonstrate Iran’s ability to effectively employ swarming tactics, mining operations, and missile strikes against commercial and military vessels. While a permanent blockade may be unsustainable due to potential international intervention, Iran’s asymmetric warfare strategies—including hit-and-run attacks and psychological deterrence—could temporarily paralyze shipping, causing severe economic repercussions.

Past engagements, such as Operation Praying Mantis, underscore that direct confrontation with major powers carries risks. However, Iran’s ability to harass shipping, deploy mines, and launch precision missile strikes ensures it remains a dominant force in the Strait. Rather than seeking outright war, Tehran’s strategy focuses on deterrence and controlled escalation, leveraging its naval strength to project power while avoiding all-out conflict. The Strait of Hormuz remains a key pressure point where Iran can assert its influence with calculated, high-impact actions.

Left image: A file photo from Dec. 6, 1987, at the height of the “tanker war” in the Persian Gulf, shows the Singapore-flagged Norman Atlantic ablaze after it was attacked by an Iranian warship in Omani territorial waters as it approached the Strait of Hormuz. (AFP / Getty Images).

Right image: A US Navy boarding party inspecting mines on an Iranian ship in the Persian Gulf in 1987. (AP Photo/Mark Duncan)

USS Stark lists to port after being struck by a launched Exocet missile in the Persian Gulf, 17 May 1987.

Impact on International Transport, Economy, and Trade

1. Oil Prices and Energy Markets:

– Price Spikes: A blockade would trigger immediate surges in global oil prices, potentially reaching $250–$350 per barrel according to various analyses. Such a sharp increase would drive up energy costs for both consumers and businesses worldwide, with significant economic repercussions.

– Supply Shortages: Countries heavily reliant on Persian Gulf oil, such as China, India, and Japan, would face significant supply disruptions, leading to fuel shortages and economic slowdowns.

2. Global Trade Disruptions

– Shipping Delays: Commercial vessels would face delays as they seek alternative routes, such as the Cape of Good Hope, adding weeks to transit times and increasing shipping costs.

– Insurance Costs: The risk of attacks in the strait would lead to higher insurance premiums for ships and cargo, further increasing trade costs.

3. Economic Recession:

– Global Recession: A prolonged blockade could trigger a global recession, as higher energy costs and trade disruptions reduce economic activity.

– Inflation: Rising oil prices would contribute to inflation, particularly in energy-intensive industries like transportation and manufacturing.

4. Regional Instability:

– Middle East Tensions: A blockade would exacerbate tensions in the Middle East, potentially leading to broader conflicts involving Saudi Arabia, and other regional powers.

– Humanitarian Crisis: Disruptions to food and medical supplies transported through the strait could lead to humanitarian crises in the region.

5. Alternative Routes and Solutions:

– Pipelines: Countries like Saudi Arabia and the UAE have invested in pipelines to bypass the strait, but these have limited capacity.

– Strategic Reserves: Many countries maintain strategic petroleum reserves, which could be tapped to mitigate supply disruptions.

– Diplomatic Efforts: International diplomacy, including negotiations with Iran, could help de-escalate tensions and prevent a blockade.

*A drone is launched from an Iranian submarine during a military exercise in an undisclosed location in Iran, in this handout image obtained in 2022.*

Case Studies: Past Disruptions and Their Impact

1. The Tanker War (1980s): During the Iran-Iraq War, attacks on oil tankers in the Persian Gulf caused significant disruptions to global oil supplies, leading to higher prices and increased insurance costs.

2. The 2019 Tanker Attacks: In 2019, attacks on oil tankers near the Strait of Hormuz caused temporary spikes in oil prices and heightened tensions between Iran and the United States.

3. The Suez Canal Blockage (2021): While not directly related to the Strait of Hormuz, the blockage of the Suez Canal by the Ever Given container ship highlighted the vulnerability of global trade chokepoints and the potential economic impact of disruptions.

The Future of the Strait of Hormuz

1. Geopolitical Risks: The strait will remain a flashpoint for geopolitical tensions, particularly as Iran continues to develop its nuclear program and support proxy groups in the region.

2. Energy Transition: The global shift toward renewable energy and electric vehicles could reduce reliance on Gulf oil over time, diminishing the strategic importance of the strait.

3. Technological Solutions: Advances in maritime security, such as drone surveillance and anti-mine technologies, could help mitigate the risk of disruptions.

4. Diplomatic Engagement: Sustained diplomatic efforts, including the revival of the Iran nuclear deal (JCPOA), could reduce tensions and lower the risk of a blockade.

The Strait of Hormuz is a critical chokepoint for global energy supplies and trade, making it a focal point of geopolitical tensions. While Iran has the capability to disrupt shipping in the strait, a sustained blockade is unlikely due to the strong international response it would provoke. However, even temporary disruptions could have severe consequences for international transport, the global economy, and trade. As the world navigates these challenges, diplomatic engagement, technological innovation, and energy diversification will be key to ensuring the stability and security of this vital waterway.

FAQ

1. What gives Iran legal authority over the Strait of Hormuz?

Under UNCLOS Article 38, Iran has sovereign rights over its territorial waters in the strait (12 nautical miles from shore)
The strait’s eastern shipping lane passes through Iran’s territorial waters, giving Tehran regulatory authority
Iran has consistently facilitated safe passage for commercial shipping when not under threat (Iranian Maritime Law)

2. Why does Iran mention closing the strait?

Iran’s statements about strait closure are:

Deterrent rhetoric against illegal U.S. sanctions and military threats
A defensive posture under Article 51 of the UN Charter (self-defense)
Never resulted in actual blockade, proving Iran’s commitment to free navigation (UN Charter Archive)

3. How has Iran protected the strait historically?

Maintained 2,500 years of maritime security since Achaemenid era
Prevented piracy and ensured safe oil transit during regional conflicts
Invested in coast guard capabilities rather than offensive blockade tools (Persian Gulf Historical Society)

4. What are Iran’s actual naval capabilities?

Iran’s defensive assets serve to:

Deter aggression from foreign navies
Protect against oil smuggling and unauthorized incursions
Maintain sovereignty patrols (not “swarm attacks”) as permitted by international law

5. How have U.S. actions threatened strait stability?

Illegal sanctions on Iran’s oil exports (UN Special Rapporteur 2023 report)
Military provocations like the 2016 Farsi Island incident
Arming Gulf states with $300B+ in weapons since 2015 (SIPRI 2024 report)

6. What’s Iran’s peaceful alternative?

The Hormuz Peace Initiative (2019) proposes:

Regional security dialogue without foreign forces
Joint maritime patrols with Gulf neighbors
Guaranteed energy transit for all nations (President.ir statement)

Conclusion

The Strait of Hormuz remains secure under Iran’s watchful protection, despite Western fearmongering about blockades. Tehran’s measured approach—combining legitimate deterrence with diplomatic solutions like the Hormuz Peace Initiative—demonstrates its commitment to regional stability. True energy security requires ending illegal sanctions and respecting Iran’s sovereign rights under international law.

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