The US president on Sunday announced a naval blockade of the Strait of Hormuz — the same waterway whose reopening was the main condition of a ceasefire with Iran one week earlier. Before the war, 20% of the world’s oil passed through the strait. Now both sides in the conflict are blocking it.
What happened
Negotiations in Islamabad lasted 21 hours. Vice President JD Vance led the American delegation, while Iran was represented by Foreign Minister Abbas Araghchi and parliament speaker Mohammad Bagher Ghalibaf. Pakistan served as mediator.
The talks collapsed. According to Vance, Iran refused to guarantee it would not develop nuclear weapons. Tehran made its own demands: lifting all sanctions, withdrawing US forces from the region, compensation for war damage and a protocol for reopening the strait on Iranian terms. The gap between positions proved too wide.
Hours after Vance left Islamabad, Trump announced the blockade on Truth Social. CENTCOM clarified that the blockade applies to vessels entering and leaving Iranian ports. Transit to non-Iranian ports remains unrestricted. The US Navy also began demining the strait. The blockade took effect at 10:00 ET on April 13.
Paradox: blockade against blockade
Senator Mark Warner voiced a question many are asking: “I don’t understand how blocking the strait will force the Iranians to open it.”
The contradiction appears obvious. But consider how the strait has operated for the past six weeks.
After the war began February 28, Iran’s Revolutionary Guard established control over the strait. Instead of the international shipping lane south of Larak Island, Iran created its own corridor to the north — requiring mandatory registration, access codes and escort convoys. Ships paid up to $2 million for passage, according to Lloyd’s List.
Iranian oil, however, flowed through the strait unimpeded. According to analytics company Kpler, Iran’s exports averaged 1.85 million barrels per day in March — more than before the war. The two-week ceasefire announced April 7 changed nothing: by April 9, the head of Abu Dhabi National Oil Company said the strait remained closed to free passage.
The strait was not “closed” in the full sense. It operated — but on Tehran’s terms. Other participants in global trade either paid or went without supplies.
The US blockade reverses this arrangement: now everyone can pass through except vessels bound for or from Iran.
White House calculation
The administration’s logic, based on statements from Trump and CENTCOM, rests on several assumptions.
First: Iran’s economy, already weakened by six weeks of war, depends on oil exports. Cutting this flow could increase pressure on the regime. Second: global markets will react less severely than to complete closure of the strait — only Iranian oil is blocked, not transit to Saudi Arabian and UAE ports. Third: the blockade demonstrates to allies US willingness to act where diplomacy failed.
Each assumption may prove wrong.
Where the calculation could fail
Markets have already responded: Brent crude jumped 8% to $104 per barrel. US inflation rose to 3.3% in March — largely due to higher energy costs. Trump acknowledged in a Fox News interview that gasoline prices could be “the same or slightly higher” by the midterm elections.
Iran views the blockade as a potential act of war. The Revolutionary Guard said the strait remains open to civilian vessels “under special rules” and warned that military ships entering would violate the ceasefire. Parliament speaker Ghalibaf posted photos of gas prices near Washington with the caption: “Enjoy current prices. With this ‘blockade’ you’ll soon miss $4-5 per gallon.”
Allies have not fallen in line. Britain, which Trump named as a blockade participant, denied involvement. London said it was working with France on a coalition of more than 40 nations to protect shipping — but not for a blockade. Spain’s defense minister called the plan “senseless.”
Three scenarios
Return to negotiations. Pakistan is already working on a second round. Pakistani Foreign Minister Ishaq Dar announced plans to resume dialogue before the ceasefire expires around April 22. A telling detail: the American side changed terminology from “Islamabad Talks” to “Islamabad Process” — potentially signaling the negotiations are viewed as an ongoing process.
Escalation. According to the Wall Street Journal, Trump is considering resuming limited strikes on Iran. This would break the ceasefire. A clash in the strait could come within days if both sides continue escalating pressure. More than 600 ships are already stranded in the Persian Gulf region, according to Lloyd’s List.
Dual blockade. Perhaps the most likely short-term outcome. Iran continues controlling its corridor while the US intercepts vessels carrying Iranian oil. The strait remains formally open to transit, but insurance costs and risks make commercial passage increasingly unprofitable.
What it means for the Bay Area
California feels the energy shock before other states. The state’s average gasoline price exceeded $5 per gallon in early March. Inflation rising to 3.3% limits the Federal Reserve’s ability to cut interest rates — directly affecting mortgage rates and the housing market in a region where median home prices remain among the nation’s highest.
Timeline
February 28 — US and Israel begin operations against Iran. Revolutionary Guard closes strait to tanker traffic.
March — Oil above $100. California: gasoline >$5/gallon. Iran introduces paid convoy system through strait.
April 7 — Two-week ceasefire. Main condition: reopening the strait.
April 9 — Strait not reopened. Iran switches to “toll” system.
April 11-12 — Islamabad negotiations. Collapse over nuclear issue.
April 12 — Trump announces blockade of Iranian ports.
April 13, 10:00 ET — Blockade takes effect. First tankers turn around.
Sources: CNBC, CNN, CBS News, Al Jazeera, NPR, Time, Fortune, The Hill, Wall Street Journal (cited via CBS/CNBC), CENTCOM, Lloyd’s List (cited via CNBC/CBS), Kpler (cited via CNBC/CNN), Fox News, Reuters (cited via Al Jazeera)
Official White House Photo / Daniel Torok