Analysts have warned that a US naval blockade of Iran would worsen the global energy crisis, with oil prices potentially rising above $150 a barrel. This follows a statement from US President Donald Trump, who announced that the US Navy would blockade the Strait of Hormuz and “interdict every vessel in international waters that has paid a toll to Iran.”

Blockade Threat Sparks Immediate Price Surge

Oil prices surged above $100 a barrel on Monday after Trump’s announcement. The move comes amid ongoing tensions in the region, with Iran having effectively closed the strait since the start of the US-Israeli war on February 28. As of Saturday. About 3,200 vessels were stranded west of the strait due to the blockage, according to the maritime intelligence company Windward.

Trump stated on Truth Social that Iran would not be allowed to profit from what he called an “illegal act of extortion.” However, the US Central Command later clarified that the blockade would affect only ships entering and exiting Iranian ports, which appears to be a scaling-back of Trump’s initial threat to fully block the strait.

Global Economic Impact of a Blockade

Trita Parsi, cofounder of the US-based Quincy Institute for Responsible Statecraft, warned that a US blockade would have a cascading impact across the global economy. “Anything that currently takes more oil off the market will push prices up, which in turn will push gas prices further,” Parsi told Al Jazeera.

Parsi also noted that if the blockade triggered retaliation from the Iran-aligned Houthis in Yemen, they could shut down the Bab al-Mandeb strait, which connects the Red Sea to the Gulf of Aden and Indian Ocean. This strait is an alternative export route for Gulf oil and gas, and a closure could lead to a sharp increase in oil prices.

Anas Alhajji, former chief economist at NGP Energy Capital Management, said that even with the US military’s assurances, expected non-Iranian ships would likely keep avoiding the strait due to elevated insurance premiums. Ships may also fear retaliation from Iran, he added.

Supply Chain and Raw Material Disruptions

The resulting rise in oil and gas prices would also cause the cost of chemicals, fertilisers, and raw materials used to make plastics to increase, according to analysts. Cameron Johnson, a senior partner at the Shanghai-based supply chain consultancy Tidalwave Solutions, said he expects prices of many raw materials to rise within several weeks if Trump makes good on his blockade threat.

“The wild card really is the timeframe on this,” Johnson told Al Jazeera. “If this is a negotiating tactic – remember we still have eight or nine days left of the ceasefire – then it may not really matter. But if this prolongs itself into the end of the month and into the first week of May, you will see prices all over the world spike for raw materials.”

Deborah Elms, head of trade policy at the Hinrich Foundation in Singapore, said the situation for global supply chains could get “much worse” under the blockade. “Some of the problems are obvious, but many are not. As an example, fabrics will get more expensive,” Elms told Al Jazeera.

Elms also noted that packaging is already a challenge for firms, with many unable to get blister packs for pills or lids for consumer goods. “We can expect consequences for food production later this year and into next year with fertiliser disruptions and lack of supply,” she said.

Chad Norville, president of the oil and gas industry news site Rigzone, said Trump’s threat is a further blow to confidence in the situation in the strait ever returning to normal. The threat alone is likely to drive up insurance premiums for shipping and logistics companies and reduce the volume of trade passing the strait each day, he said.

“Disruptions to shipping and elevated risk in the region were already well established due to the conflict,” Norville told Al Jazeera. “This threat doesn’t create that baseline. It amplifies it by reinforcing uncertainty around one of the world’s most critical chokepoints.”