Iran has sharply increased attacks on vessels traversing the Strait of Hormuz, potentially endangering the recent recovery in Persian Gulf oil exports.

Although shipping volumes through the strait had rebounded to near pre-conflict levels earlier this month, shipping industry participants say there are signs that cargo traffic through the waterway may be slowing.

However, oil loading data observed at several major producing countries in the region shows no clear evidence of a change in transport volumes. One shipowner stated that vessel passage through the Strait of Hormuz does not appear to be restricted.

Hostilities in the Middle East are escalating, with Saudi Arabia suffering a series of attacks from Yemen's Houthi rebels. The deteriorating situation pushed London crude prices above $106 per barrel on Monday, though prices edged slightly lower on Tuesday.

The UK Maritime Trade Operations (UKMTO) reported that on October 11, four tankers were each struck by unidentified flying objects while transiting the chokepoint, roughly double the daily average number of attacks the agency had observed over the previous week.

Growing evidence suggests ship operators are becoming more cautious. Tanker tracking data shows that more than a dozen very large crude carriers and several Suezmax tankers turned around or altered course as they approached Fujairah in the UAE, near the entrance to the Strait of Hormuz.

Shipbrokers and some shipowners operating in the region also cited other signs of a shipping slowdown, particularly longer waiting times for ship-to-ship transfers. However, one shipowner involved in such operations said he had not felt any slowdown.

Ship-to-ship transfers have played a critical role in driving the recovery of oil exports from the region. Under this model, shuttle tankers assume the risk of transiting the Strait of Hormuz, then transfer their cargo to other vessels, which ultimately deliver it to buyers.

Before the latest round of escalation, Shell CEO Wael Sawan estimated last week that Middle East oil transport volumes had recovered to about 80% of pre-conflict levels. Russell Hardy, head of major energy trader Vitol Group, said on October 6 that 12 million barrels of crude oil and another 2 million barrels of fuel were being shipped out of the Strait of Hormuz daily.

Satellite imagery of oil export terminals inside the Persian Gulf shows no signs of a significant slowdown in transport. However, because these images can only be obtained intermittently, they reflect only part of the picture.

At Saudi Arabia's oil terminals in the Persian Gulf, loading activity has slowed from the surge seen in late September. Eight images captured by the EU's Sentinel 1 and Sentinel 2 satellites over the seven days ending October 12 showed that an average of four out of seven loading buoys were in use, compared with five to six during the earlier loading surge.

On the two trading days this month for which Sentinel 2 satellite imagery was available, five to six tankers were visible loading at southern Iraqi oil terminals each day, consistent with the loading pace observed in the second half of September.