Strait of Hormuz blockade and other major naval sieges in modern times

A "shadow fleet" of vessels successfully bypassed a US naval blockade of the Strait of Hormuz between March 1 and April 15, 2026, following an escalation of conflict involving Iran. This covert network of ships utilized fake flags, shell companies, and disabled tracking signals to navigate the vital waterway, which is crucial for global oil transport. The blockade was imposed by the United States on April 13 after Iran threatened to block enemy ships. Despite the blockade, an investigation tracked 202 voyages by 185 vessels through the strait, demonstrating Iran's ability to evade international maritime restrictions. This operation occurred amidst fears of attacks and disruptions to navigation in the strait, a chokepoint for a fifth of the world's oil.

During a rally in Florida, Donald Trump described a US Navy operation to seize a ship amid an American blockade of Iranian ports, stating the navy acted "like pirates." This occurred as legal experts expressed concerns over Iran's blockade of the Strait of Hormuz and its intention to charge passage fees. Iran effectively closed the strait, a crucial oil and gas route, following a US-Israeli air campaign. The US announced its blockade of Iranian ports last month after peace talks failed. The US Central Command has redirected numerous vessels to enforce compliance with the blockade, which the Pentagon stated will continue indefinitely and applies to all ships entering or leaving Iranian ports. Iran has pledged to maintain its control of the strait as long as the US blockades its ports.

President Donald Trump has warned Iran to comply with US demands regarding its nuclear program, stating that a US naval blockade could continue for months. Trump conveyed this message on Wednesday, reportedly after rejecting Iran's latest proposal to reopen the Strait of Hormuz. He urged Iran to "get smart soon" and indicated a willingness to extend economic pressure. The US naval blockade is aimed at compelling Iran to accept tighter controls on its nuclear activities. Trump's remarks were made via his social media platform, accompanied by a graphic image.

Pakistan has opened six overland transit routes to Iran to facilitate trade amid disruptions caused by US-Iran tensions and a blockade of the Strait of Hormuz. The initiative, formalized on April 25, 2026, allows goods from third countries to be transported through Pakistan to Iran by road, addressing the issue of thousands of stranded containers at Karachi port. These routes connect Pakistan's major ports, including Karachi and Gwadar, with Iranian border crossings in Balochistan. The move aims to promote regional trade and position Pakistan as a key trade corridor. The announcement occurred during Iranian Foreign Minister Abbas Araghchi's visit to Islamabad, where Pakistan is seeking to mediate an end to the conflict between the US and Iran. The transit order does not include Indian-origin goods.

As the ceasefire between the U.S. and Iran nears expiration this week, Iran is reaffirming its threat to block ships in the Strait of Hormuz if the U.S. does not lift its blockade of Iranian ports. Iranian parliamentary Speaker Mohammed Bagher Qalibaf stated that Iran will continue to target commercial vessels in the critical waterway, through which a significant portion of the world's oil passes. This announcement follows an incident on Saturday where Iranian forces fired on ships attempting to transit the strait, forcing them to turn back. The situation threatens to escalate the global energy crisis and potentially lead to renewed conflict. Pakistani mediators are attempting to facilitate further negotiations between the U.S. and Iran before the ceasefire ends on Wednesday.

The U.S. military announced it will begin a blockade of all Iranian ports and coastal areas starting Monday, following unsuccessful ceasefire talks with Iran in Pakistan. U.S. Central Command stated the blockade will be enforced against all vessels entering or departing Iranian ports on the Arabian Gulf and Gulf of Oman, but ships traveling between non-Iranian ports will still be allowed to transit the Strait of Hormuz. This announcement halted the limited ship traffic that had resumed in the strait since the ceasefire. The blockade is intended to pressure Iran, which has continued to export oil despite sanctions. President Trump also criticized Pope Leo XIV after the Pope denounced the war and called for peace negotiations.

An Iranian general threatened to halt Red Sea traffic if the U.S. military continues its blockade of Iranian ports. The warning, issued by Maj. Gen. Ali Abdollahi Aliabadi, stated that the blockade creates insecurity for Iranian commercial vessels and could violate the U.S.-Iran ceasefire. He asserted that Iran would not allow exports or imports in the Persian Gulf, Sea of Oman, and Red Sea if the blockade persists. The U.S. Central Command reported stopping nine vessels attempting to break the blockade, all of which were oil tankers. The White House stated that the blockade is effective and that the U.S. has made its redlines clear to Iran.

Following a brief reopening, Iran's Islamic Revolutionary Guard Corps (IRGC) Navy has reasserted control over the Strait of Hormuz, threatening to target any vessel attempting passage until the US lifts its naval blockade on Iranian vessels and ports. This action reverses a previous decision to open the strait as part of a ceasefire agreement. The IRGC claims the US blockade violates the ceasefire. Iranian parliament speaker Mohammad Bagher Ghalibaf criticized the US blockade as a "clumsy and ignorant decision," emphasizing Iran's control over the Strait. The Strait of Hormuz is a critical shipping lane in the Persian Gulf and the Sea of Oman.

Over 10,000 US troops are currently enforcing a blockade on Iranian ports as of April 2026. The US military has issued warnings to Iran-linked ships, stating that force, including warning shots and potential boarding, could be used if they attempt to breach the blockade. In the first three days of the operation, 14 ships turned around to avoid confrontation. Vessels approaching the blockade, which is enforced in Iranian territorial seas and international waters, receive warnings via radio broadcast. The US Central Command has stated its readiness to use necessary force to ensure compliance with the blockade.

Amidst a ceasefire in April 2026, the US is maintaining economic pressure on Iran, including a naval blockade, to expedite negotiations. Iranian Foreign Minister Araghchi announced the Strait of Hormuz was open to commercial vessels following a coordinated route, a move acknowledged by US President Trump. However, the US blockade will remain until a complete agreement is reached. US Secretary of Defence Hegseth threatened attacks on Iranian civilian infrastructure if diplomacy fails. Chinese analysts suggest this intensified economic pressure from the US could prolong the conflict, despite the US intention to force Iran to negotiate.

On April 14, 2026, the United States implemented a naval blockade of Iran to pressure the country into accepting terms to end their ongoing war. Iran's armed forces have condemned the blockade as an illegal act. The blockade threatens Iran's oil revenue, as approximately 80% of its exports pass through the Strait of Hormuz. While Iran had been controlling access to the Strait, allowing only select countries to pass, it continued to export its own energy products. In March and early April, Iran's oil exports actually increased, reaching 1.84 million barrels per day in March. The price of Iranian oil has remained above $90 per barrel in the past month.

Oil prices surged on Sunday after the U.S. announced it would begin blockading Iranian ports on Monday. U.S. crude rose 8% to $104.24 a barrel, and Brent crude increased 7% to $102.29. The blockade, enforced by U.S. Central Command, aims to restrict access to all Iranian ports on the Persian Gulf and Gulf of Oman but will allow passage through the Strait of Hormuz for ships traveling between non-Iranian ports. The Strait of Hormuz is a crucial waterway for global oil shipping, with approximately a fifth of the world's traded oil passing through it daily. Analysts suggest the blockade could further tighten oil markets and potentially influence ongoing negotiations with Iran, though concerns exist about the potential for increased economic strain worldwide.

Amid a fragile ceasefire between the US and Iran, three oil supertankers exited the Strait of Hormuz on Saturday, according to shipping data. The vessels, the Liberia-flagged Serifos and the China-flagged Cospearl Lake and He Rong Hai, are each capable of carrying 2 million barrels of oil. The Strait of Hormuz is a critical chokepoint for global oil and liquefied natural gas shipments. The Serifos, chartered by Thai state-owned PTT and carrying crude from Saudi Arabia and the UAE, is expected to arrive in Malaysia on April 21. The Cospearl Lake, laden with Iraqi oil, is headed to China, while another tanker, Ocean Thunder, chartered by a unit of Petronas, transited the waterway last week.