Iran threatens to close the Strait of Hormuz

Tehran has warned that it will reimpose strict control over the Strait of Hormuz and potentially halt commercial traffic if the United States does not lift its naval blockade of Iranian ports. The threat comes hours after Iran's Foreign Minister announced that the strategic waterway was "completely open" to commercial vessels during the current ceasefire in Lebanon.

The Strait of Hormuz remains the world's most critical energy chokepoint, through which approximately one-fifth of global oil consumption and a significant share of liquefied natural gas (LNG) typically transits. Any sustained disruption would have immediate and severe consequences for global energy markets.

Global oil prices reacted sharply to the renewed uncertainty. Brent crude futures rose as traders assessed the risk of renewed supply disruptions. While Iran briefly allowed limited commercial traffic on April 17, shipping companies remain cautious, with reports of vessels turning away and insurance costs staying elevated.

Background on the Blockade

The United States imposed a targeted naval blockade on April 13, preventing ships from entering or exiting Iranian ports while stating that traffic not destined for Iran could continue through the strait. President Trump has repeatedly said the blockade will remain in force until a comprehensive agreement with Iran is reached. Iranian officials describe the measure as “economic strangulation” and “piracy,” using it to justify their control over the waterway.

U.S. Central Command has clarified that the operation is limited to Iranian ports and is not a full blockade of the Strait of Hormuz itself. However, Tehran maintains that as long as the port blockade continues, the strait will remain under “strict management and control” by Iranian armed forces.

Naval and diplomatic posture

U.S. forces have repositioned carrier strike groups and increased aerial surveillance in the region to deter any Iranian attempts at mining or vessel interdiction by the Islamic Revolutionary Guard Corps Navy (IRGCN). Diplomatic efforts continue in multiple channels, including Geneva and Doha, with European Union representatives urging immediate de-escalation.

Officials have stressed that any attempt to close the Strait of Hormuz would violate freedom of navigation principles under the United Nations Convention on the Law of the Sea (UNCLOS) and could trigger a broader regional conflict.

As of April 18, the situation remains fluid. Iran has reverted the strait to a “previous state” of tight control, while the U.S. blockade on its ports continues. The international community is watching closely to see whether this exchange marks another round of brinkmanship or the start of a more dangerous escalation.