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.

Global famine fears are escalating due to the ongoing crisis at the Strait of Hormuz, which analysts warn could lead to an eight-year disruption similar to the Suez Canal closure of 1967-1975. The U.S. naval blockade of Iranian ports and Iran's effective closure of the Strait have strained fragile food supply chains and driven up prices. While a diplomatic resolution could reopen the Strait within weeks, it would still take months for supply chains to normalize. In the worst-case scenario, the Strait could remain closed for an extended period, significantly impacting global trade and food security, particularly due to disruptions in fertilizer transport.

The US Treasury Department has threatened shipping firms with sanctions if they pay tolls to Iran, warning that non-US persons could face legal consequences if such payments facilitate sanctions violations. This action comes as Iran has been targeting ships in the Strait of Hormuz following attacks by the US and Israel. The US has also imposed a naval blockade since April 13th, significantly reducing ship traffic through the vital waterway. The Treasury also sanctioned three Iranian currency exchange houses involved in converting oil revenue. These measures aim to pressure Iran's revenue streams, impacting global trade and humanitarian aid delivery due to increased costs and delays.

Iran's national currency, the rial, has hit new lows against the US dollar, trading at over 1.81 million to the dollar on Wednesday. This sharp decline is attributed to a US naval blockade and existing sanctions, which are impacting Iran's trade, particularly with China and the UAE. The currency's value has plummeted significantly over the past year, exacerbated by unchecked inflation and economic mismanagement. In response, Iranian authorities are attempting to mitigate the impact by empowering border provinces for essential goods imports and allocating funds for food purchases. The US Central Command stated the blockade has effectively cut off Iran's economic trade.

Iran may be forced to cut oil production if the US naval blockade of the Strait of Hormuz persists, according to experts. Analysis suggests Iran could exhaust its crude oil storage capacity within 12 to 22 days. The Strait of Hormuz, a vital waterway for global oil and LNG supplies, has been partially or fully restricted by Iran since February 28, coinciding with air strikes by the US and Israel. Iran claims the security of the strait is not free and links its openness to the lifting of US restrictions on its oil exports. The US naval blockade began on April 13, leading to concerns about Iran's ability to export its oil and manage its storage levels.

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.

In April 2026, analysts warned that a planned US naval blockade of Iran, announced by President Trump, would worsen the global energy crisis. While Central Command stated the blockade would only affect ships entering and exiting Iranian ports, experts believe it could still cripple international shipping. The blockade, intended to prevent Iran from profiting from "illegal extortion," could drive oil prices above $150 a barrel if it provokes retaliation, such as the Houthis shutting down the Bab al-Mandeb strait. This action marks a policy reversal, as the US had recently waived some Iranian oil export sanctions to ease the energy crunch. Since the start of the US-Israeli war in February, Iran has already restricted traffic through the Strait of Hormuz, causing thousands of vessels to become stranded.

A US naval blockade of the Strait of Hormuz is raising the specter of a major energy crisis in Asia. The blockade, initiated by the US to pressure Iran into peace talks and reopening the strait, has prompted Iranian threats against all ports in the Persian Gulf and Gulf of Oman. The Strait of Hormuz is a critical chokepoint for global energy supplies, particularly for Asia, through which nearly 90% of the region's crude oil transits. China, India, Japan, and South Korea are especially vulnerable, relying on the strait for a large majority of their oil imports. With peace talks stalled, the timeline for resuming oil flows remains uncertain, threatening significant economic disruption in Asia.

Oil prices rose above $100 per barrel on Monday after ceasefire talks between the U.S. and Iran failed to end their ongoing war, which began in late February. Despite the breakdown in negotiations, U.S. stock markets remained relatively stable, suggesting cautious optimism about the conflict's potential impact on the global economy. The S&P 500 was virtually unchanged, while the Dow Jones Industrial Average was down 0.5% and the Nasdaq composite rose 0.3%. President Trump threatened a blockade of the Strait of Hormuz in response to the failed talks, aiming to restrict Iran's oil revenue. Iran retaliated by threatening all ports in the Persian Gulf and the Gulf of Oman. The Strait of Hormuz is a crucial waterway for global oil transport.

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.

The US military, through CENTCOM, announced it will blockade all Iranian ports starting Monday, April 13th, at 10 am Eastern Time, impacting all maritime traffic entering or exiting. This action follows unsuccessful peace talks in Pakistan and aims to exert pressure on Tehran. While the blockade targets vessels of all nations using Iranian ports, CENTCOM stated it will not impede vessels transiting the Strait of Hormuz to and from non-Iranian ports. Iran has warned that any approaching military vessels will be breaching the ceasefire. The announcement has already impacted oil prices, with US crude jumping 8 percent. The blockade comes after Iran effectively took control of the Strait of Hormuz following the start of war with the US and Israel on February 28th.

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.