A strait does not become dangerous on the day a missile lands on a tanker. It becomes uninsurable, which is a slower and more consequential process, and the machinery that does the insuring is small enough to fit around a London committee table. Understanding its habits explains the pattern the 2026 war has followed: traffic keeps moving through waters that are plainly risky, while prices absorb the danger before anyone else does.
Two policies, one hull
A ship generally sails with ordinary marine insurance covering the sea itself: weather, grounding, machinery failure, cargo damage. Those policies exclude war, capture, terrorism and similar perils. A separate war policy picks those up, and the premium on it is charged per transit through areas the market considers exposed.
The listed area is the pivot of the whole system. The Joint War Committee, made up of hull underwriters and brokers from the London market, publishes the areas it regards as exposed to war, terrorism, piracy and related risks. Its judgement is not law. It is a recommendation, and the market treats it as decisive: a ship entering a listed area notifies its underwriters, pays an additional war risk premium, and often accepts conditions such as routing restrictions and reporting requirements.
The 2024 Red Sea crisis put the committee's role on public display for the first time in a generation. When the listed area expanded, insurance costs for a single transit rose from a negligible fraction of hull value to figures in the percent range, and the additional premium for a large container ship ran into hundreds of thousands of dollars per voyage. Those numbers then reappeared in freight rates, which is why a conflict corridor can raise prices in shops that never see a ship.
What the 2026 war changed
The war with Iran altered two things at once. The Gulf became a war zone rather than a transit risk, and the Red Sea's southern exit fell under the control of a force that has attacked shipping before. For underwriters the question shifted from how much to charge for risk to whether the risk can be priced at all.
Two market behaviours are worth separating. The first is repricing: additional premiums for transits in the affected areas were reported at multiples of pre war levels, and the standard discount structures that reward operators for safety records were largely suspended. The second is withdrawal: some capacity simply left the segment, either because underwriters declined specific routes or because their own reinsurers restricted the cover they would pass on. When the reinsurance layer tightens, primary insurers tighten with it, and the effect arrives as refusals rather than as prices.
There is a third behaviour that gets less attention: temporal. Insurance prices lag events because underwriting is backward looking, set from loss records that take months to compile, and then updated in discrete review cycles. A market that reprices today is using evidence from weeks ago. That lag cuts both ways. It can keep a risky route cheap for too long, and it can also prefer caution long after the danger has moved, which is why the market sometimes penalises a strait that has gone quiet and is relaxed about one that has not.
Why the ships still sail
If premiums are onerous and some underwriters refuse, why is there traffic at all? For three reasons. First, war risk cover is not one product: it is a stack of hull, cargo and liability layers written by different pools, and even when some capacity leaves, others stay for the price. Second, operators are contractually obliged. A tanker chartered to lift a cargo from a Gulf port that is physically able to load has a commercial duty to attempt the voyage, and the cost of refusing can exceed the premium. Third, and most importantly, someone is always willing to carry the risk at a higher number: the war risk market historically firms at every escalation and settles once loss experience accumulates.
The party that pays is settled, usually unromantically, by the fine print of the charter. Under the standard war risks clauses in use in the trade, additional premiums for deviations into listed areas are commonly for the charterer's account or shared under a formula, and cargo war risk sits with the cargo owner. In practice the smaller and more desperate the buyer, the more of the premium they absorb, because the largest charterers negotiate caps and the smallest take the market rate.
Reading the insurance market as a warning system
For anyone trying to track when a corridor is becoming genuinely unusable, the listed area decisions beat the news cycle as a signal, for one structural reason: underwriters settle the loss, so they price what they can prove, and their pricing is visible across the whole market at once. A premium that stops rising after a wave of incidents usually means the market has stopped expecting worse. A refusal pattern, where certain carriage is declined outright, is the louder alarm, because it means the reinsurance behind the primary cover has stepped away.
The war has also made a quieter change permanent: insurance documentation has become an enforcement tool. Authorities checking tanker compliance increasingly treat the certificate of insurance as evidence of the trade's legitimacy, and a fleet built on self certified cover is now visible precisely because it cannot produce a certificate any conventional underwriter would sign. What began as a risk price has become a filter, and the ships that pass through it are increasingly the ones the system believes.
The insurance market will not end the war, and it cannot close a strait. What it can do, and does, is decide at what price a hull is willing to pass. When that price is quoted, the rest of the economy is already paying it, whether or not the ships are still visible on the map.