A satellite map of ships in the Strait of Hormuz on Monday, April 20, 2026.Marine Vessel Traffic
“If it works, it’s not great for the US. And if it doesn’t work, it’s also not great for the US.”
That’s what Jeff Colgan, a political science professor and director of the Climate Solutions Lab at the Watson Institute for Public and International Affairs at Brown University, told me last week about the US naval blockade on Iranian ports.
The Trump administration’s stated intention was to stop Iran from profiting off the closure of the Strait of Hormuz. At the time, Iran’s government only allowed its own ships, and those of some of its allies, safe transit in the waterway. Iran was also reportedly charging tolls for at least some other ships to pass through the Strait of Hormuz, a key waterway in the Persian Gulf through which approximately 20 percent of global crude oil and natural gas flowed before the US and Israel launched strikes on Iran starting in February. Much of that oil went to Asian countries, with China, India, and Japan as the primary importers.
The US military implemented the blockade last Monday in response, saying last Tuesday that global sea trade with Iran had “completely halted.” But as Colgan says, “there’s this kind of Catch-22”: the more effective the US military blockade is, “the more it ripples out to global energy markets and affects everybody,” including voters “who are not going to be pleased with higher prices.”
Since I spoke with Colgan on Wednesday, oil prices have risen even further. Despite the ceasefire between the US and Iran established earlier this month, few ships have been able to cross the strait. As I recently reported, Iran reportedly shot at two Indian-flagged ships on Saturday and Trump said on Sunday that Marines stormed and seized an Iranian cargo ship trying to run its blockade “by blowing a hole in the engineroom.”
On Friday, Trump said that the naval blockade would “remain in full force” until Iran agreed to a deal, while Iran has vowed to not open the strait until the US withdraws its blockade, which it argues violates the ceasefire agreement.
In short, although the US and Iran now appear set to continue peace negotiations in Islamabad, don’t count on significant advances anytime soon.
Many reports on the fight for control of Hormuz hinge on national governments’ claims about poorly documented conflict at sea; tracking individual ships in the region is overwhelming, and verifying the bulk of military statements is nearly impossible.
That’s partly the usual “fog of war,” Colgan says, but it’s exacerbated by what he calls the Trump administration’s “casual relationship with truth.”
Oil markets, ship transits, and other bellwethers of the ceasefire are fluctuating wildly. As a way of tracking what’s going on, Colgan says those types of assessments are doubtful at best.
But one measurement that remains palpable for American consumers is the gas pump. According to Brown University’s Climate Solutions Lab, Americans have spent $23.4 billion more on gasoline and dieselsince the start of the war on February 28. That comes out to $178.43 per household in the US, as the national average price of gasoline has increased by more than a third to $4.04 per gallon and diesel prices have risen by just over 50 percent.
