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

What is a Naval Blockade and How Would It Work in the Strait of Hormuz?

The U.S. military announced plans to enforce a maritime blockade targeting all vessels entering or exiting Iranian ports, effective Monday. This move allows ships from other nations to transit the Strait of Hormuz, a vital waterway Iran has previously restricted in response to U.S.-Israeli attacks. The decision follows stalled negotiations between the two sides, which began on 28 February.

President Donald Trump stated that direct discussions in Pakistan collapsed because Iran “refused to relinquish its nuclear aspirations.” In response, the Iranian foreign ministry criticized the U.S. for “excessive demands and unlawful requests.” On Sunday, Trump emphasized the blockade’s scope in a post on Truth Social, declaring the U.S. would “blockade any and all ships attempting to enter or leave the Strait of Hormuz.”

“I have directed our Navy to intercept every vessel in international waters that has paid a toll to Iran. No ship violating this toll will receive safe passage on the high seas,” Trump wrote.

According to the 2022 U.S. Navy Commander’s handbook, a blockade is defined as a “belligerent operation to prevent vessels and/or aircraft from entering or exiting specified ports, airfields, or coastal areas under enemy control.” Trump initially claimed the blockade would commence “immediately,” later clarifying it would be “effective pretty soon” but described it as an “all or none” strategy.

The U.S. Central Command (Centcom) confirmed the blockade’s implementation at 10:00 EDT (15:00 BST) on Monday, stating it would apply to all vessels transiting Iranian ports and coastal zones. However, the operation would not hinder ships moving between non-Iranian ports, with a formal notice provided to commercial mariners beforehand.

Trump hinted at international collaboration, though he did not name specific allies. The BBC reports the UK will not join the effort, despite being a NATO member. A UK government spokesperson reiterated support for “freedom of navigation” and noted the strait “must not be subject to tolling.” They are collaborating with France and others to establish a coalition for the waterway’s reopening.

NATO has pledged assistance in clearing the strait, with Trump stating it would be “free to use again in not too long a distance.” The U.S. and UK are deploying minesweepers, as the president claimed, “I understand the UK and a couple of other countries are sending minesweepers.” The UK has already positioned mine-hunting systems in the region.

Legal analysts in the U.S. raised concerns about potential breaches of maritime law. One questioned whether the military enforcement of the blockade would undermine the current ceasefire agreement. The strait’s strategic location has long enabled Iran to exert influence, blocking vessels to inflate oil prices. By closing the passage, Trump aims to disrupt Iran’s revenue streams, though this could escalate tensions.

Iran has imposed hefty fees on certain ships, using the strait as leverage. The blockade’s success in severing this income source depends on its ability to enforce restrictions without provoking further conflict. Analysts warn that the measure might risk destabilizing the region, particularly if Iran retaliates against U.S. forces or commercial traffic.