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

Donald Trump announced that the U.S. Navy would begin a naval blockade of the Strait of Hormuz, targeting vessels that have paid tolls to Iran. According to the U.S. Central Command (Centcom), the blockade would be enforced impartially against vessels entering or departing Iranian ports and coastal areas, starting Monday at 10:00 EDT. The U.S. Navy Commander's handbook defines a blockade as preventing vessels and aircraft from entering or exiting specified areas controlled by an enemy state. Trump stated the blockade would be effective soon and involve other countries, with NATO potentially assisting in clearing mines. The UK will not be involved in the blockade. The stated aim is to ensure free passage through the Strait of Hormuz, which Trump accuses Iran of hindering.

The US military, through Central Command (CENTCOM), has announced a complete blockade of Iranian ports, halting all sea-based economic trade. Implemented within the last 36 hours, the blockade involves over 10,000 US armed forces members, warships, and planes. CENTCOM is enforcing the blockade against all vessels entering or leaving Iranian coastal areas and ports. According to CENTCOM, six merchant ships complied with US orders to turn around in the first 24 hours, and a US Navy destroyer interdicted two oil tankers attempting to leave Iran. US President Trump hopes the blockade will compel Iran to accept US terms for ending the US-Israel war on Iran, following failed negotiations in Pakistan.

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.

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.

Following the failure of peace talks, the United States initiated a naval blockade of Iranian maritime trade on April 13th, according to a US Central Command announcement. The blockade targets all maritime traffic entering and exiting Iranian ports. This action follows a declaration by President Trump. Despite losses suffered by the Iranian navy, Chinese analysts suggest that Iran's small, fast-attack boats may pose a challenge to the US Navy's blockade operations in the Strait of Hormuz. The blockade was launched after peace talks in Pakistan failed.