In the Strait of Hormuz, through which about 20% of the world's oil flows, a fresh series of attacks by Iranian forces on oil tankers and a renewed American naval blockade have cut traffic to its lowest level since May. Three vessels of cargo type crossed the waterway this week, compared with 11 a day before and about 125 ships before the war started. Shipping data this week shows. Not one Very Large Crude Carrier or LNG carrier made an attempt at the crossing day by day, as they had done the previous two days.

The numbers tell only part of the story. Kpler tracking data indicates that two sanctioned product tankers and one small liquefied petroleum gas (LNG) ship left the strait through Iranian waters on Thursday, but then they came to a halt in the Gulf of Oman where the U.S. Navy blockade has now been formed. An Iraqi bunkering tanker returning from the Gulf with fuel oil cargo hours after it was diverted from the strait on Friday. There were two supertankers, each with two million barrels of crude, that did slip through earlier in the week en route to Japan and Turkey as a reminder that, despite all the chaos, there's still some flow.That traffic bust is now manifesting in all the other numbers that count: insurance books, refinery plans, price quotations in Tokyo, Mumbai and Rotterdam. Brent crude ended near $88 a barrel on Thursday, gaining about 14 percent in a week for a third consecutive weekly increase, and West Texas Intermediate crude surpassed $82. Both benchmarks have now wiped out the recovery from a US-Iran memorandum of understanding signed in mid-June that briefly allowed the strait to reopen, and even led the US Energy Information Administration to revise its full-year Brent price projection to $82 a barrel. That prediction is already out of date.

It's time that the marine insurers put a price tag on the fear. Hull war-risk premiums have increased to 3-10 percent of the insured value of a ship, from about a quarter of one percent prior to the renewed fighting in the Hormuz area. To an owner of a hundred million dollar tanker that is the difference between spending about $250,000 for one transit and spending up to $10 million. Brokers call the market a “rollercoaster,” which follows the price of oil virtually to the millimetre. Several hundred vessels, including crude carriers and those carrying gas, are now at anchor offloading in the Gulf and its approaches rather than take the risk of crossing, while maritime officials estimate several thousand seafarers are effectively “locked in” in the danger area as the International Maritime Organization tries to work out safe evacuation corridors.The military side of these numbers has been falling by the day. This is the sixth night of strikes by American forces in a week, which targeted an airport and bridges, and were expanded to the Tehran area, while Iranian authorities report that several were killed in the southern province. Washington has also attacked maritime infrastructure directly, such as the downing of what seemed to be a tower at Iran's Chabahar port on the Gulf of Oman. In response, Iran has fired on U.S. forces in Qatar and attacked Bahrain, Jordan and Kuwait, including hitting the country's electrical grid and causing an hour's delay in power distribution while authorities urged people to conserve electricity. Tehran's Revolutionary Guard has flatly said it opposes any oil or gas flowing through Hormuz until the U.S. attacks cease and its diplomatic sources have told the Houthis in Yemen to be prepared to block the Bab al-Mandeb strait at the mouth of the Red Sea if the U.S. strikes at Iran's power infrastructure. That would add a second line of trouble to the world's energy plumbing at a time when the first line is already jammed. Even those that aren't directly at war are feeling the effects of the war Iraq briefly suspended loadings at its Basra terminal on Thursday after a drone strike before resuming hours later.

When viewed from a broader perspective, the pattern is more than a localized outbreak it's a structural test of a global economy that still relies on a few choke points. About one-fifth of the world's oil and an equivalent amount of liquefied natural gas rely on 21 miles of water between Iran and Oman remaining open, and there is no viable alternative shipping line of that magnitude that works out to the cost of an oil bill from New Delhi to Berlin. Those most vulnerable are Asian refiners who import the majority of Gulf oil, but the reverberations extend beyond the Gulf leg as European gas buyers backstabbed by the Red Sea turmoil of the last two years watch a second corridor shake, insurers factor in a second energy inflation shock as they start to price risk on the tanker fleet, and central banks in Frankfurt to New Delhi must consider another energy-powered inflation shock as they begin to talk rate cuts. The ongoing developments in the Gulf is not only a regional military issue. It's a real-life example of how assumptions that have been taken for granted for decades over the cheap, reliable and just-in-time delivery of goods globally can unravel, and how little buffer the system has to absorb the next shock, no matter where it comes from next.