What Happened
- The United States announced a naval blockade of Iranian ports starting April 13, 2026, after peace talks between the two countries collapsed over the weekend, primarily because Iran refused to abandon its nuclear weapons programme.
- US forces began blocking ships from entering or exiting Iranian ports near the Strait of Hormuz, with the US Central Command clarifying the blockade would not impede freedom of navigation for non-Iranian ports.
- President Trump stated the US Navy would "seek and interdict every vessel in International Waters that has paid a toll to Iran," aiming to deny Iran oil export revenues while the rest of the world suffers from Hormuz disruption.
- Iran threatened a "severe" response; Pakistani Prime Minister Shehbaz Sharif stated a ceasefire was "holding" and that diplomatic efforts were under way.
- Oil prices surged past $99 per barrel (Brent) immediately following the blockade announcement, adding to earlier peaks of $119 and record Dubai crude prices of $166 reached in mid-March 2026.
Static Topic Bridges
The Strait of Hormuz: Geography and Strategic Significance
The Strait of Hormuz is a narrow waterway located between Iran to the north and Oman and the UAE to the south, connecting the Persian Gulf with the Gulf of Oman and the Arabian Sea. At its narrowest navigable point it is about 33 km wide. It is classified as a maritime chokepoint — a narrow channel along widely used global sea routes whose disruption can cause supply delays and price spikes.
- In 2024, approximately 20 million barrels per day (mb/d) of petroleum passed through the strait, representing about 20% of global petroleum liquids consumption
- Nearly 34% of global crude oil trade transits the strait, with most exports destined for Asia
- Approximately one-fifth of global LNG trade also transits the strait, primarily from Qatar
- Only two shipping lanes — each 3 km wide — are used for transit (inbound and outbound), separated by a 3 km buffer zone
Connection to this news: The US blockade specifically targets Iranian ports along this strait, attempting to cut off Iran's oil export revenues while declaring that non-Iranian vessel navigation would not be impeded — raising contested questions of international maritime law.
Naval Blockade under International Law
A naval blockade is a form of economic warfare that prevents ships from entering or leaving an enemy's ports. Under international law, a blockade during armed conflict is regulated by customary law and the San Remo Manual on International Law Applicable to Armed Conflicts at Sea (1994). A blockade must be declared, effective, and applied impartially to all nations to be considered lawful.
- UNCLOS (United Nations Convention on the Law of the Sea, 1982) guarantees the right of "transit passage" through straits used for international navigation (Articles 37–44)
- Transit passage cannot be suspended even by coastal states — it applies to all ships and aircraft, including warships
- Neither the US nor Iran is a party to UNCLOS, but many provisions are considered customary international law
- The US maintains this is not a full blockade of the strait but a targeted blockade of Iranian ports only, distinguishing it from closure of the strait itself
Connection to this news: The US legal justification hinges on the distinction between blockading Iranian ports (permitted as a belligerent measure) and restricting freedom of navigation through the international waterway (which would violate customary law).
Iran's Nuclear Programme and JCPOA
The Joint Comprehensive Plan of Action (JCPOA), signed on July 14, 2015, was an agreement between Iran and the P5+1 (US, UK, France, Russia, China + Germany) to limit Iran's nuclear programme in exchange for sanctions relief. The US withdrew from the JCPOA in 2018 under President Trump's first term. Iran subsequently began ignoring its nuclear limitations.
- By early 2024, Iran was estimated to have enriched sufficient material for three nuclear weapons
- In 2025, the IAEA formally declared Iran non-compliant with nuclear obligations
- On September 28, 2025, UN sanctions were reimposed on Iran (the "snapback" mechanism)
- The collapse of April 2026 peace talks centred on Iran's refusal to surrender its nuclear weapons ambitions
Connection to this news: The failure of the nuclear file is the direct proximate cause of the breakdown in peace talks, which in turn triggered the US decision to impose the blockade.
Key Facts & Data
- Brent crude surged past $99/barrel after the blockade announcement; peak was $119/barrel in March 2026
- Dubai crude hit a record $166/barrel on March 19, 2026
- The Strait of Hormuz handles ~20 mb/d of oil — approximately 20% of global petroleum consumption
- ~34% of global crude oil trade transits Hormuz, plus ~20% of global LNG trade
- JCPOA signed July 14, 2015; US withdrew in 2018; UN sanctions reimposed September 28, 2025
- The strait's navigable channel is approximately 33 km wide at its narrowest point
- Tanker traffic through the strait had dropped to near-zero following the February 28, 2026 Hormuz closure by Iran