Shipping through the Strait of Hormuz slowed sharply after a commercial vessel was struck while transiting the strategic waterway, underscoring how fragile maritime security remains despite a tentative US-Iran understanding to de-escalate regional tensions.

Data from maritime analytics firm Kpler showed 29 commodity vessels crossed the strait on Saturday, followed by just 12 on Sunday. That compares with a midweek surge in activity after Tehran and Washington signed a memorandum of understanding that briefly reassured shippers and pushed crossings to 70 on Wednesday, the highest level since the Middle East conflict began.

The latest incident appears to have rattled that fragile confidence. The targeted vessel was hit on Saturday morning while moving through the strait, prompting ships to continue for several hours along a southern corridor that runs through Omani waters before traffic visibly thinned, according to MarineTraffic, a tracking platform owned by Kpler.

Iran has warned commercial operators against using what it calls unapproved shipping lanes, but tankers and container ships continued to navigate multiple routes through the narrow chokepoint over the weekend. The strait handles a significant share of the world’s seaborne oil and liquefied natural gas exports, making any disruption closely watched by energy markets and naval powers alike.

Tracking data captures only vessels with their transponders switched on, meaning the true number of crossings may be higher if some ships chose to “go dark” for security reasons. Analysts say total figures are likely to rise as satellite imagery and delayed position reports are incorporated.

More ships entered the Gulf than departed over the weekend, reversing the pattern of the previous week, when naval escorts and commercial operators focused on evacuating crews trapped in Gulf ports. A UN-led mission to extract some 11,000 seafarers was suspended after another vessel was struck in the Gulf of Oman, further complicating logistics for shipping companies.

On Sunday, four tankers and a container ship used the southern Omani corridor to enter the Gulf under escort from US Navy vessels, according to industry monitoring. No ships used that route to exit the Gulf the same day, Kpler reported.

Iran said it has held an initial meeting with Oman on joint management of the strait, while Washington has signaled it will not accept any transit fees for passage through what it insists is an international waterway.