Iran’s effective lockdown of the Strait of Hormuz, meant as retaliation against the US-Israeli strikes in recent weeks, has threatened to turn one of the world’s most critical maritime chokepoints into a militarised toll booth.Iran has reportedly charged a $2 million transit fee to ships from certain friendly nations. Despite the limited pause in hostilities with the ceasefire agreed to on Wednesday (April 8), the uncertainty in the region continues to send shockwaves through the global economy. Iran has insisted that ships can pass only with its permission and in coordination with its armed forces. The Strait of Hormuz is the narrow waterway connecting the Persian Gulf and the Arabian Sea.But such a use of the maritime chokepoint is not without historical precedent. The current crisis is also the culmination of a long legal and asymmetric military strategy adopted by the Islamic Republic to weaponise Hormuz.Stakes for kingdoms and companiesManipulation of the Strait of Hormuz for political reasons is as old as its use as a trade route. The strait has served as an important maritime crossroads (and indeed, an asset) for the better part of 4,000 years.Under the imperial control of the Kingdom of Hormuz between the 10th and 13th centuries, its importance was elevated by the empire’s relocation to Hormuz Island (then known as “Jarun”) in the hopes of leveraging the passage to their benefit. Functioning similarly to a modern toll system, the strait was subject to economic policies and the collection of customs duties from passing ships.The strait’s vulnerability is sharply accentuated by its physical limitations. While the Strait of Hormuz is roughly 167 km long, it is just 33 km wide at its narrowest point between Iran and Oman. Critically, given the depth required for massive commercial oil tankers means that the actual navigable shipping lanes are a mere three kilometres wide in each direction, separated by another three-kilometre buffer zone.Explained | US-Iran ceasefire: Why oil and gas markets are not returning to normal anytime soonWith the Industrial Revolution and the advent of the East India Company in the Middle East in later centuries, the British Empire further commercialised the strait to facilitate speedier transport of its spice vessels.Story continues below this adOver the last 120 years, the narrow corridor has enjoyed a status of importance, given its vitality to the flow of oil. Estimates by the International Energy Agency state that the strait facilitates the passage of roughly 20 million barrels of oil per day (about 20% of the global tally), alongside moving a third of the world’s LNG in circulation.Questionable legality of tollsAdopted in 1982 and in effect since 1994, the United Nations Convention on the Law of the Sea (UNCLOS) is the primary doctrine guiding international maritime law. Applicable to all international straits, the treaty allows ships to enjoy the right of “transit passage” with unimpeded entry.Express research | Indian merchants and the rise of Hormuz in global tradeComplications arise from the fact that while Iran signed the UNCLOS, it never ratified it. Tehran relies instead on the older 1958 Geneva Convention framework, arguing it only recognises the right of “innocent passage”. This distinction allows a coastal state to reserve the right to unilaterally suspend innocent passage, should it deem a vessel’s presence a threat to its national security.Having explicitly voted against non-suspendable passage during the original UNCLOS negotiations, Iran preserved this legal loophole, allowing it to restrict access.Story continues below this adFurther, the actual navigable lanes fall within the “territorial sea” limits claimed by both Iran and Oman. Measured upto 12 nautical miles from a coast’s baseline, states can exercise sovereignty within this limit. Iran thus argues these waters do not constitute an international high-seas corridor.Iran’s post-1979 escalationFollowing the 1979 Islamic Revolution, Tehran invested heavily in developing its military architecture. Going back to the Iran-Iraq War at the dawn of the 80s, Tehran first tested the adoption of an asymmetric warfare strategy through the use of sea mines and missiles against commercial shipping tankers.Known in subsequent years as the tanker theory, the acquisition of the Greater and Lesser Tunb islands — a stone’s throw from the shipping lanes — fortified the Iranian state’s grip over the strait. Evolving into a core mandate executed by the Islamic Revolutionary Guard Corps (IRGC) Navy, which was established as a formidable security force after the revolution, the last decade in particular saw significant investments into Iran’s asymmetric capabilities.Multiple decentralised anti-ship missile batteries along the coastline, stockpiles of sea mines and fleets of fast attack crafts (FACs) are the most common measures employed by the IRGC during coastline skirmishes.Story continues below this adWith the FACs designed to swarm and seize commercial tankers, Iran effectively backed up its legal claims of distinguishing between “innocent” and “transit” passage. They would help enforce Tehran’s view that passage through the strait would be a privilege granted by Iran and not a right guaranteed by international law.2026: The boiling pointBy January 2026, the Iranian regime was navigating severe internal frictions owing to massive anti-government protests. Tehran accelerated its external aggression, presumably hoping to stifle any perceptions of weakness within the international community.The turmoil brought Iran and the United States to the negotiating table once again, but sudden US and Israeli strikes targeting Iran’s top political leadership derailed any hopes of normalisation. It became the catalyst triggering Tehran’s decision on Hormuz, which had been hinted at during past conflicts, but never actually undertaken.Solidified by the Iranian parliament approving a formal motion to close the strait to “hostile” nations, the strait once again began undergoing militarisation along with the imposition of heavy tolls. Tehran’s demands for a $2 million transit fee per commercial vessel have forced shipmasters to coordinate their passage directly with the Iranian armed forces. To ensure compliance, the IRGC Navy is again utilising FACs to physically lock down transit lanes.Story continues below this adExpert Explains | How Iran’s power pyramid came to be, with Supreme Leader at the topIran, however, is also attempting to fracture the international response by carving out specific conditions for passage. Tehran is granting unhindered passage to vessels from allied nations, primarily China and Russia, with some Indian ships also having crossed over of late. Complicating the possibility of a unified global coalition, this leaves the US military struggling to dismantle an asymmetric blockade that predominantly targets Western-aligned shipping.Vision for the futureIran’s long-term aims are centred around transitioning this wartime blockade into a permanent, institutionalised chokehold. Currently advancing legislation to codify permanent transit taxes, the Iranian parliament seems to be essentially abandoning the UNCLOS framework.Additionally, the IRGC has also issued new mandatory maritime maps, using the persistent threat of unmapped sea mines to force all vessels into highly restricted entry and exit corridors under direct Iranian surveillance. In a step towards bypassing Western financial sanctions, Tehran has also proposed an unprecedented system demanding digital cryptocurrency payments for these tolls.By intertwining the threat of immediate destruction for non-compliant vessels with these new bureaucratic and financial hurdles, Iran’s ultimate objective is clear — dictating the terms of global energy transit to its advantage for the foreseeable future.