What is a naval blockade and how would it work in Strait of Hormuz?

April 13, 2026

The United States has announced a naval blockade of Iranian ports beginning Monday, aimed at preventing vessels from entering or leaving the Strait of Hormuz while allowing ships traveling to non-Iranian destinations to pass freely. This action follows failed negotiations between the US and Iran that broke down over multiple issues including Iran's nuclear program and control of the strategic waterway. Iran had previously closed the strait in response to US-Israeli strikes and has been charging fees for some vessels to transit through it, despite a ceasefire agreement requiring safe passage.

Who is affected

Iran and the Iranian government
US military forces and US Central Command (Centcom)
President Donald Trump
Shipping companies and vessels attempting to navigate the Strait of Hormuz
Commercial mariners operating in the region
Countries and consumers dependent on oil and gas shipments through the strait
UK Prime Minister Sir Keir Starmer and the UK government
France and other coalition partners
NATO member countries
Republican Congressman Mike Turner and Senator Mark Warner

What action is being taken

The US military is implementing a blockade of maritime traffic entering and leaving Iranian ports beginning at 10:00 EDT (14:00 GMT) Monday
US forces are allowing ships traveling to and from non-Iranian ports to pass through
The US Navy is seeking to interdict vessels in international waters that have paid tolls to Iran
The US is destroying mines that Iran allegedly laid in the strait
The UK is urgently working with France and other partners to form a coalition to protect freedom of navigation
British military mine-hunting systems are already deployed in the region

Why it matters

The Strait of Hormuz is a critical waterway for global oil and gas shipping, with an average of 138 ships passing through daily before the conflict began. Iran's closure and selective control of this narrow passage has given it significant geopolitical leverage, allowing it to spike oil prices and generate revenue through transit fees while disrupting global commerce. The US blockade represents an escalation that could cut off Iranian government revenue but risks further increasing energy prices worldwide. The action also raises legal questions about violations of maritime law and the current ceasefire agreement, potentially jeopardizing diplomatic efforts to end the broader conflict that began on February 28.

What's next

US Central Command will provide additional information to commercial mariners via a formal notice before the blockade starts
The US will bring in minesweepers to clear the strait
Trump stated that "at some point" an agreement on free passage will be reached
Most shipping companies will continue to wait and see whether a tentative peace agreement emerges and whether that might hold, potentially leading to a slow ramping up of shipping activity

Read full article from source: BBC