Iran's Islamic Revolutionary Guard Corps warned shipowners on Wednesday that any new transit route through the Strait of Hormuz established without coordination with Tehran is "unacceptable and dangerous," threatening actions against vessels that ignore its instructions.
The stern warning underscores Tehran's resolve to retain control over the Strait of Hormuz and to resist transits that bypass its authorization. It also highlights the lingering uncertainty facing shipowners navigating the Strait even after the U.S. and Iran signed a memorandum of understanding last week to reopen the strategically vital energy artery.
The IRGC Navy said that only the shipping routes designated by Iran are permitted for passage, and that coordination with Iranian forces via the designated communication channel is mandatory, according to Iranian local media.
"Navigation outside these routes is highly dangerous and prohibited, and we warn all vessels to strictly avoid any movement outside the designated corridors," the IRGC Navy said, according to the report.
The warning came after a key naval information group had proposed alternative shipping corridors on Saturday, asking shipowners to consider transiting the strait along the southern route with their transponder signals on. "The southern transit route, along Omani [territorial waters], has been confirmed clear of mines and is the recommended route," the notice said.
Traffic data pointed to a tentative recovery. Transits tripled to 93 last weekend compared with the prior comparable period, according to ship-tracking data provider MarineTraffic, but remain far below pre-war levels when more than 100 ships transited the strait each day.
MarineTraffic also confirmed 31 verified crossings on Tuesday by commercial and energy-laden vessels, as shipowners continued to use a mix of Iranian, Omani, and International Maritime Organization route patterns through the chokepoint. "Operators are still moving cautiously rather than returning to fully normal traffic patterns," the firm said Thursday.
The U.S. Treasury sanctioned Iran's Persian Gulf Strait Authority in May, describing it as an attempt to "extort global maritime trade." Treasury Secretary Scott Bessent also warned that Washington would not tolerate any tolling system on Hormuz, saying his agency would aggressively target any actors involved.
Analysts have warned that any form of Iranian control could have long-term effects on oil flows through the Strait, as transits may not fully recover to pre-war levels if Tehran retains strategic control of the waterway.
Oil tanker traffic through Hormuz before the war might represent the high point for transits for the foreseeable future, said Helima Croft, head of global commodity strategy at RBC Capital Markets. "Any end to the conflict that leaves Iran exercising operational control and influence over the Strait will result in appreciably lower flows through the waterway in our view," Croft told clients in a Thursday note.
— CNBC's Spencer Kimball contributed to this report.