Iran earned nearly $5bn in oil exports in the past month while it shut the strait for most other ships. That revenue is at risk.
(Al Jazeera) – The United States naval blockade of Iran has come into effect as President Donald Trump’s administration tries to pressure Tehran into accepting its terms for an end to their war by trying to squeeze the Iranian economy.
The blockade began at 14:00 GMT on Monday. Iran’s armed forces have called it “an illegal act” that “amounts to piracy”.
Even though Iran has become accustomed to US sanctions and has continued to function during the war, a blockade like this could inflict significant damage to Iran’s economy, analysts said.
How much can this blockade hurt Iran? Here’s what we know:
How will the blockade hurt Iran’s oil revenue?
Iran primarily exports oil and gas through its ports. Soon after the start of the US-Israel war on Iran on February 28, authorities in Tehran announced what amounted to a closure of the Strait of Hormuz, the only waterway out of the Gulf, through which 20 percent of the world’s oil and gas supplies pass in peacetime.
The near-shutdown of the vital chokepoint sent global oil and gas prices soaring, and since then, Iran has controlled the strait: Only ships from a few countries that struck individual deals with Tehran were allowed through.
But throughout that period, Iran itself continued to export its energy products through the strait.
Iran’s oil exports through the Strait of Hormuz account for about 80 percent of its total exports. According to Kpler, a trade intelligence firm, Iran exported 1.84 million barrels per day (bpd) of crude oil in March and has shipped 1.71 million bpd so far in April, compared with an average of 1.68 million bpd in 2025.
