US blockade on Iran’s oil begins amid unclear enforcement, energy shock fears
The move threatens to cut off roughly 2 million barrels per day of Iranian crude exports, but key questions remain as the operation begins.
A US naval blockade targeting Iranian oil shipments came into force at 10 a.m. EST on Monday, marking a new escalation in the US-Israel-Iran conflict just one week after a fragile ceasefire was announced.
The move threatens to cut off roughly 2 million barrels per day of Iranian crude exports, tightening global supply amid a historic energy disruption. But as the operation begins, key questions remain, from how the blockade will be enforced to how Iran and global markets will respond, raising the stakes for regional security and the world economy.
What happened: On Sunday, US Central Command announced it would begin enforcing a blockade on maritime traffic entering and exiting Iranian ports, including those beyond the Strait of Hormuz along the Gulf of Oman, starting Monday morning. The directive follows the collapse of US-Iran talks over the weekend in Islamabad, casting doubt on the ceasefire announced last Tuesday.
According to a CENTCOM press release, the blockade will be applied “impartially against vessels of all nations” entering or leaving Iranian ports, while allowing transit through the Strait of Hormuz for ships heading to non-Iranian destinations. Mariners have been advised to monitor official notices and coordinate with US naval forces in the region.
However, critical details remain unclear, including the scale of US naval deployment and whether other nations will cooperate as Washington's NATO allies have signaled they will not participate.
The scope of the operation may also prove narrower than President Donald Trump’s earlier rhetoric suggested. In a Truth Social post Sunday, Trump said the US would begin “BLOCKADING any and all Ships trying to enter, or leave, the Strait of Hormuz,” adding that vessels paying Iranian tolls would be interdicted and that US forces would destroy Iranian-laid mines. “THIS IS WORLD EXTORTION,” he wrote.
Conflicting signals have also emerged from key players. Iran has denied charging tolls for passage, with its ambassador to India saying Monday that no such fees have been imposed on Indian vessels.
Meanwhile, early signs point to confusion in the shipping market. According to global trade intelligence firm Kpler, there was a modest uptick in transit activity through Hormuz over the weekend, but flows remain far below pre-conflict levels. “The lack of clarity around enforcement at sea is likely to deter broader participation,” the firm said Monday, noting that shipowners, charterers and insurers are acting cautiously.
Why it matters: At its core, the blockade is a high-risk attempt to cut off Iran’s main economic lifeline amid faltering efforts to reopen the Strait of Hormuz — a chokepoint that typically handles about 20% of global oil and liquefied natural gas flows.
If successful, Trump’s strategy could force Iran to cut a deal, as lost exports would erode Tehran’s leverage. In practice, however, it could prove complex and prolonged, with no guarantee of success.
Iran has continued exporting close to 2 million barrels per day during the conflict, according to Kpler, even as transit routes have been disrupted. Blocking those flows would remove a significant source of global supply as oil prices climbed back above $100 per barrel on Monday.
At the same time, the move risks provoking retaliation and further destabilizing a ceasefire set to expire next week. It also shifts the conflict into a new stage: an effort to police one of the world’s most strategic waterways.
There are also limits to how quickly Iran can adapt. Like its Gulf neighbors, Iran relies heavily on Hormuz to export crude and has limited ability to bypass the waterway. Its main alternative is the Jask export terminal on the Gulf of Oman, connected to a pipeline designed for up to 1 million bpd but operating far below that level. Kpler data suggests actual capacity is closer to 300,000 bpd — a fraction of volumes typically shipped from Iran’s Kharg Island inside Gulf waters.
More broadly, the blockade marks a new stage in a historic energy shock. Kpler notes that risk in the Strait of Hormuz is shifting from physical disruption to regulatory and enforcement ambiguity, a dynamic that could suppress shipping activity even without direct attacks. Ultimately, the move represents a gamble, testing not only Iran’s ability to withstand economic pressure but also how much more disruption battered global energy markets can absorb.
