The Strait of Hormuz has traditionally presented shipowners with a brutal but relatively understandable calculation.

Enter the Strait and accept the risk.

Avoid it and stay away from the most dangerous part of the conflict.

That calculation is becoming much harder.

Commercial vessels have now been attacked not simply while attempting to negotiate the Strait of Hormuz, but while anchored elsewhere in the Gulf and operating in neighbouring territorial waters.

A seafarer has been killed. Another is missing.

A tanker carrying approximately two million barrels of Iraqi fuel oil has been struck by a drone.

Several merchant vessels have been reported hit by disabling fire.

And Brent crude is holding above US$100 a barrel as the international oil market absorbs the consequences.

The development raises a disturbing new question for the global shipping industry:

What happens when avoiding the chokepoint no longer means avoiding the war?

A seafarer killed off Dubai

One of the most serious incidents involved the Gibraltar-flagged oil-products tanker Hercules Star.

The vessel's charterer, Peninsula, said one seafarer was killed and another was missing following an incident while the tanker was at anchorage off Dubai.

The location is important.

The vessel was not simply a tanker attempting to force its way through the most dangerous section of the Strait of Hormuz.

It was at anchor.

The UK Maritime Trade Operations agency separately reported a vessel in the area listing after apparently being struck by a projectile, although the precise circumstances of the incidents remain subject to investigation.

The death changes the nature of the commercial risk.

War-risk insurance can place a financial value on a ship and its cargo.

It cannot make the voyage safe for the people aboard.

Two million barrels attacked in Iraqi waters

Another significant incident occurred in Iraqi territorial waters.

The Panama-flagged New Andros, carrying approximately two million barrels of Iraqi fuel oil, was struck by a drone.

A fire broke out.

Iraqi authorities said the vessel suffered minor hull damage, but its 22 crew members were unharmed and there was no reported leakage of the cargo.

Responsibility for the attack has not been established.

That qualification matters.

In a conflict filled with claims, counterclaims and deliberate information warfare, attribution should follow evidence rather than assumption.

But the physical event itself is established.

A tanker carrying an enormous energy cargo was attacked inside Iraqi waters.

Once again, it was not simply a vessel caught while attempting to traverse Hormuz.

Several merchant ships hit

The UK Maritime Trade Operations agency has also reported several merchant vessels being struck by disabling fire in the northern Gulf and Gulf of Oman.

Iran says it attacked 10 ships near Hormuz — eight tankers and two American vessels — following US attacks that destroyed five Iranian oil tankers.

Those claims and individual incidents require careful separation.

An Iranian statement that it intends to attack something is rhetoric.

A claim that it has attacked a particular vessel requires verification.

A damaged merchant ship, a burning tanker and a dead crew member are physical consequences.

The distinction is essential.

The latest events provide enough independently confirmed evidence to conclude that the commercial maritime environment has materially deteriorated.

Hormuz is barely functioning normally

At the same time, traffic through the Strait remains extraordinarily depressed.

Preliminary Kpler tracking data recorded only six commodity vessels passing through Hormuz on Tuesday, compared with nine the previous day and a recent 10-day average of about 12.

Before the war, approximately 125 large commercial vessels normally passed through the Strait each day.

Not all of those vessels carried oil or LNG, and some ships may now cross with their identification systems switched off.

Nevertheless, the contrast is extraordinary.

Rystad Energy estimates that oil flows through Hormuz recently fell below two million barrels a day after recovering to around eight to nine million barrels a day before the latest fighting resumed.

The Strait is not completely closed.

But describing it simply as "open" increasingly tells us very little about whether it is functioning as a normal international trade route.

Brent above US$100

The oil market is responding.

Brent crude settled on Wednesday at US$101.21 a barrel, after reaching US$101.58.

It was the highest closing level since May.

The price matters, but the reason behind it matters more.

Markets are not simply responding to inflammatory statements from Tehran or Washington.

Tankers have been attacked.

Saudi energy infrastructure has come under attack.

Hormuz traffic remains severely constrained.

Insurance costs have risen enormously.

Alternative export routes are under pressure.

And merchant vessels are increasingly being caught directly in military operations.

The risk premium therefore has physical foundations.

The geography of risk is expanding

For months, the Strait itself has dominated discussion.

That was understandable.

Before the war, roughly one-fifth of global oil and LNG supply passed through this narrow waterway between Iran and Oman.

But energy transportation does not begin and end at the Strait.

Ships wait at anchorages.

Tankers load at terminals.

Some vessels store oil offshore.

Cargoes can be transferred between ships.

Alternative pipelines move crude towards ports outside Hormuz.

Refineries process crude into usable fuels.

Those products then have to be loaded onto another generation of vessels and transported to consumers.

Every part of that chain depends upon places where ships and infrastructure can operate with an acceptable level of risk.

That is why attacks outside the immediate Hormuz transit corridor matter.

A dangerous passage can be avoided. A disappearing safe harbour cannot.

Insurance cannot solve everything

The economics of shipping through the region have already changed dramatically.

An Emirates National Oil Company executive has estimated that combined costs associated with moving some cargoes through Hormuz can now reach US$10 million to US$20 million.

Cargo insurance can represent a substantial percentage of cargo value, while war-risk premiums have risen sharply.

Some participants have reportedly contemplated operating without insurance.

Others simply do not want to send their vessels into the region.

That produces a self-reinforcing problem.

Fewer willing ships can mean higher freight rates.

Higher risk means higher insurance.

Longer routes consume more fuel and vessel time.

Tankers unavailable in one region can tighten shipping capacity elsewhere.

And all those costs eventually become part of the price of the commodity being transported.

But insurance has an important limitation.

It can compensate for a financial loss.

It cannot prevent a missile or drone from striking a vessel.

And it cannot compensate adequately for the loss of a human life.

Australia is part of this maritime system

Australia is geographically distant from the Persian Gulf.

Economically, it is much closer.

Australia depends heavily on international maritime supply chains for refined petroleum products, particularly petrol, diesel and aviation fuel.

Those products participate in Asian markets influenced by the availability and price of crude, refining capacity, freight rates and shipping risk.

Australia therefore does not need to import a particular cargo directly through Hormuz to experience the consequences of disruption there.

If Gulf oil becomes harder to move, Asian refiners compete for alternatives.

If tanker availability tightens, freight costs rise.

If insurance becomes more expensive, delivered fuel costs increase.

If diesel markets tighten, Australian transport, agriculture, construction and mining businesses eventually encounter those costs.

And when businesses pay more to move goods, some portion of that cost can ultimately reach households.

The connection between a drone striking a tanker in Iraqi waters and the Australian cost of living may appear remote.

The international petroleum market makes it considerably shorter.

The next danger

The most important development to watch now is whether attacks continue expanding geographically.

If merchant vessels become vulnerable not only while crossing Hormuz but while anchored, loading, storing cargo or operating in neighbouring waters, the shipping industry's response could become more consequential than any formal declaration that the Strait is closed.

Owners can avoid a particular channel.

They can delay a transit.

They can sail under naval protection.

They can reroute.

But an international energy system cannot function normally if ships cannot identify somewhere reasonably safe to wait, load and operate.

That is the threshold the Gulf must avoid crossing.

The Times View

For decades, Hormuz was understood as a geographical problem.

There was a dangerous narrow passage. The challenge was getting ships through it.

The present conflict is turning that simple map into something much more complicated.

Tankers have been attacked outside the Strait. A commercial seafarer has been killed while his vessel was at anchor off Dubai. A tanker carrying two million barrels of Iraqi fuel oil has been struck inside Iraqi territorial waters. Saudi energy infrastructure and alternative export routes have also come under pressure.

The safe areas around the original danger zone are becoming less clearly defined.

That matters because world trade depends upon more than navigable water.

It depends upon confidence that ships can load, sail, anchor and unload without becoming participants in somebody else's war.

A dangerous passage can be avoided. A disappearing safe harbour cannot.

For Australia, the lesson is again one of energy security.

We cannot control the Strait of Hormuz. We cannot control the Gulf war. We cannot determine whether a foreign shipowner accepts a particular voyage or whether an insurer is prepared to cover it.

But we are exposed to the consequences of all those decisions.

The greatest danger therefore may not be the dramatic moment when somebody announces that Hormuz has been closed.

It may be something quieter.

The ships simply decide there is nowhere safe enough to go.