Iran Closes Strait of Hormuz Again as Fresh Tanker Attacks Reported
Tehran, 18 April 2026
Iran’s military has reimposed strict control over the Strait of Hormuz on Saturday, reversing Friday’s reopening announcement and effectively closing the critical shipping lane that carries 20% of global oil supplies. The closure follows continued US naval blockades of Iranian ports and reports of Revolutionary Guards firing on tankers attempting passage. Despite a 10-day Lebanon cease-fire raising hopes for regional stability, the strategic waterway remains contested as diplomatic talks in Pakistan struggle to bridge US-Iran differences, keeping global energy markets on edge.
Dramatic Reversal Shatters Brief Diplomatic Breakthrough
The closure represents a stark reversal from Friday’s diplomatic breakthrough, when Iran’s Foreign Minister Abbas Araghchi announced the strait was “completely open” for the remaining period of the cease-fire [1]. That announcement prompted US President Donald Trump to declare the “Hormuz Strait situation is over” and claim Iran had “agreed to everything” [1]. However, the optimism proved short-lived as Iran’s military issued a statement on Saturday declaring the strait had “returned to its previous state” and was now “under strict management and control of the armed forces” [1]. This dramatic shift occurred less than 24 hours after the initial reopening, highlighting the fragility of diplomatic progress in the ongoing conflict that began on 28 February 2026 [1].
Revolutionary Guards Fire on Vessels as Tensions Escalate
Fresh attacks on commercial shipping underscore the deteriorating security situation in the waterway. The UK Maritime Trade Operations Centre (UKMTO) reported that Iranian Revolutionary Guards fired at a tanker on Saturday, forcing two vessels to turn back from their intended routes [1][3]. MarineTraffic tracking data revealed that two Indian-flagged vessels, the cargo ship JAG ARNAV and the oil tanker SANMAR HERALD, were forced to make U-turns after being denied access by Revolutionary Guards officials near Larak Island [3]. The SANMAR HERALD, carrying a full cargo load with a draught of 21 metres and likely originating from Iraq, exemplifies the commercial disruption facing oil shipments [3]. These incidents add to a troubling pattern, with US Central Command reporting that 23 ships have been turned back since the American naval blockade of Iranian ports began on 13 April [3].
US Blockade Continues Despite Cease-Fire Agreements
The underlying cause of Iran’s closure decision stems from the US maintaining its naval blockade of Iranian ports despite the Lebanon cease-fire. Admiral Brad Cooper, head of US Central Command, confirmed the maritime blockade on ships entering and exiting Iranian ports “remains in effect until further notice” [1]. Trump reinforced this position on Truth Social, stating that “the blockade will remain in place until any deal with Iran is 100% complete” [1]. The US has deployed more than a dozen Navy ships across the Gulf of Oman, with Cooper noting American forces have “eyes on every single one of them” [1]. This continued enforcement contradicts Iranian expectations that the Lebanon cease-fire would lead to broader de-escalation, with Iran’s parliament speaker Mohammad Bagher Ghalibaf having warned that passage through the strait would be based on Iranian authorisation if the blockade remained [1].
Economic Impact and Uncertain Diplomatic Prospects
The renewed closure threatens to exacerbate already significant economic damage from the two-month conflict. Iranian government spokeswoman Fatemeh Mohajerani estimated Iran has sustained at least $270 billion in damages from the war, with reconstruction projected to take at least 12 years [1]. Oil markets, which saw Brent futures fall 9% to around $90 per barrel on Friday following reopening news, now face renewed uncertainty [1]. International Energy Agency data suggests that an estimated 10% of global oil supply has been disrupted, with more than 80 energy facilities in the region damaged [1]. Meanwhile, diplomatic efforts continue with Pakistan facilitating talks, as Field Marshal Asim Munir concluded a three-day visit to Iran on Saturday [1]. However, analysts remain cautious about prospects for a comprehensive agreement, with Crisis Group’s Ali Vaez noting the sides remain “miles away from a comprehensive agreement” [1]. The current cease-fire is set to expire next week, around 24 April 2026, with Trump threatening renewed strikes if no deal is reached [2].