On the fourth day of the U.S. naval blockade of Iranian ports, the situation in the strategically important Strait of Hormuz remains tense. The United States is tightening control measures, while Tehran threatens to destabilize traffic in the Red Sea in response. Although some commercial vessels are managing to pass, hundreds of tankers remain blocked in the region, creating uncertainty for global oil and goods supplies.
Vessel-tracking data paint a mixed picture. In the past day more than 20 commercial ships passed through the strait, including tankers carrying corn, methanol and other cargoes. However, the overall situation is far from normal — over 800 oil tankers are still at anchor, hesitant to transit. This points to serious disruptions in Persian Gulf logistics chains.
The so-called "shadow fleet" of Iran, made up of hundreds of old tankers, plays an important role in evading sanctions. These vessels use various masking methods: turning off tracking systems, changing flags and documentation, and conducting ship-to-ship oil transfers in open sea to hide the oil’s origin and destination. Such tactics allow Tehran to sustain part of its exports despite pressure from Washington.
U.S. forces are using a phased approach toward violators of the blockade. It includes aerial and maritime surveillance using planes, drones and satellites, as well as direct warnings to vessels. Six tankers have already been forced to turn back after receiving such signals. In extreme cases the U.S. may board or even detain ships, although such operations face logistical difficulties due to the remoteness of the region.
The Strait of Hormuz is critical to the global economy — about one-fifth of the world’s consumed oil passes through it. The legal status of the strait is disputed: the U.S. and Iran rely on different international conventions, complicating crisis resolution. Tehran insists on its right to control passage of ships it deems "threatening," while Washington appeals to freedom of navigation.
Three main approaches to managing the strait are currently under discussion. The Iranian option envisions possible transit fees and restrictions for "hostile" countries. The American plan bets on military escort of ships and increased pressure on Tehran. Europeans, for their part, propose creating a multinational mission to ensure free navigation, fearing that any transit fees could set a dangerous precedent in international maritime law.
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Which specific international conventions on the right of passage through straits do Iran and the U.S. invoke to justify their positions, and why do their interpretations diverge? - The primary document is the United Nations Convention on the Law of the Sea (UNCLOS) of 1982, which the U.S. has not ratified but considers reflective of customary international law. Iran is also not a party to UNCLOS, yet both sides refer to its provisions on transit passage through international straits (Part III). Divergences arise in interpretation: the U.S. insists on a broad right for warships to exercise innocent transit without prior notification, while Iran, as a coastal state, argues it has the right to regulate passage and demand notification or authorization for warships, especially in its territorial waters near islands, citing security concerns.
How does the logistics of Iran’s "shadow fleet" operations in the Persian Gulf actually work, for example, where do ship-to-ship transfers typically occur and how are these actions coordinated? - The logistics of the "shadow fleet" involve using aging tankers with AIS transponders switched off to conceal locations. Ship-to-ship transfers often take place in open waters in several key zones: east of the Strait of Hormuz in the Gulf of Oman, off the coast of the UAE, and in more distant areas such as off Singapore or in the South China Sea. Actions are coordinated through complex networks of intermediaries, shell companies, renaming of ships and flags, and encrypted communications. Iran frequently uses its coastal waters and islands for initial stages of such operations.
What is the historical context of Iran’s control over the Strait of Hormuz, and how does this relate to its islands such as Abu Musa, Tonb-e Bozorg and Tonb-e Kuchak? - Historical Iranian control over the waters of the strait traces back to ancient Persian empires. The modern context formed in the 20th century. The islands of Abu Musa and the Greater and Lesser Tunbs (Tonb-e Bozorg and Tonb-e Kuchak) are strategically located at the entrance to the Strait of Hormuz. Iran established control over them in 1971, a day before the formation of the UAE, a claim disputed by the UAE. Iran regards these islands as an integral part of its territory based on historical ties and agreements with the sheikhdoms of Ras al-Khaimah and Sharjah (predecessors of the UAE). Control of these islands allows Iran to strengthen its position in regulating navigation through the strait, as they are used for military facilities and expanding territorial waters.
Full version: 4 أيام من الحصار الأمريكي.. ما وضع الملاحة في "هرمز"؟