Oil flows through the Strait of Hormuz nearly tripled while the Memorandum of Understanding (MoU) between the United States and Iran was in effect, though it remained far below pre-war levels, according to ship tracking data.

Some 374 million barrels of oil exited the Gulf during the 60-day window covered by the since-expired MoU, equalling about 6.1 million barrels per day, trade intelligence firm Kpler said in a briefing published on Wednesday.

In the period from April until the MoU was signed on June 17, an average of 2.3 million bpd were exported via the Gulf, Kpler said.

While the MoU led to a significant boost in oil flows, volumes only reached about 40 percent of the roughly 15 million barrels that transited the Strait of Hormuz each day in 2025, according to Kpler.

More than half of the shipments occurred in the first three weeks of the agreement, and “by the end the flow was thinner, darker and re-accumulating behind the chokepoint”, said Emmanuel Belostrino, head of Global Crude and Geopolitical Market Data at Kpler.

The MoU, announced on June 17 following a flurry of diplomatic activity primarily facilitated by Pakistan, expired on Monday without a peace deal in place amid stalled negotiations between Washington and Tehran.

The expiration of the MoU, which US and Iranian officials cast as a step towards a permanent end to the war, came as attacks on commercial shipping in the Strait of Hormuz continued to cast a shadow over one of the most critical nodes in the global energy supply chain.

Five commercial vessels have been attacked in the strait over the past week, according to the UKMTO Operations Centre, including a cargo ship that reported being struck by an unknown projectile off Oman on Tuesday, resulting in the death of one seafarer.

The International Association of Dry Cargo Shipowners (INTERCARGO), a trade association, identified the deceased mariner as a crew member on board the Liberia-flagged bulk carrier Minoan Dignity.

“Behind every vessel caught up in conflict are seafarers – civilians carrying out their professional duties, far from their homes and families, who keep global trade moving,” INTERCARGO said in a statement.

“INTERCARGO reiterates its fundamental position: seafarers are civilians and must never become targets or collateral victims of geopolitical conflicts.”

No government or group has claimed responsibility for the attack, the first such incident involving a confirmed death since July.

At least 18 seafarers have been killed in attacks on commercial vessels in the region since the US and Israel launched their war on Iran in late February, according to the International Maritime Organization.

Iranian forces have claimed responsibility, or been blamed for, dozens of attacks on commercial shipping since the start of the war.

US forces have acknowledged responsibility for about half a dozen attacks, including a June 10 strike on a Palau-flagged tanker that killed three Indian seafarers.

The critical strait, a conduit for about one-fifth of the global oil supply before the war, saw 73 transits between August 10 and 16, down from 91 the previous week, according to preliminary data from Lloyd’s List Intelligence.

Oil prices edged higher on Thursday, with Brent crude futures up about 0.3 percent at $91.93 per barrel as of 06:00 GMT.

Tim Waterer, chief market ‌analyst at Australia-based KCM Trade, said markets anticipate further declines in oil flows amid the impasse between Washington and Tehran.

“The market isn’t convinced by the more optimistic take from the US administration on the security of passage through the Strait,” Waterer told Al Jazeera.

“Until there is clearer evidence of sustained, safe transit and a more durable diplomatic framework, confidence among operators is likely to stay low and volumes are unlikely to recover meaningfully,” Waterer said.