War-Gaming Maritime Chokepoints Before Disruption Hits

War-gaming has become a standard part of supply chain risk management.

Most firms run exercises to understand how their networks respond to disruption, whether that is a port closure, a blocked canal, or a geopolitical escalation. The objective is clear: anticipate the impact, define a response, and avoid being caught off guard.

However, it's become clear that maritime chokepoints such as the Strait of Hormuz, the Red Sea, and the Suez Canal do not disrupt in a single, defined moment. Pressure builds over time, behaviour begins to shift, and the system starts to adjust before anything formally closes.

That matters because it changes what war-gaming needs to capture.

The real challenge is not simply how a supply chain responds once a chokepoint fails, but how its options evolve as pressure builds, and how early decisions begin to shape outcomes while the system is still functioning.

What disruption actually looks like

When tensions escalated at the end of February, shipping did not suddenly collapse. It began to change shape.

Carriers suspended transits through the Strait. Major lines paused services entirely. Tankers already inside the Gulf struggled to exit, while incoming traffic dropped sharply. Within days, vessel movements fell dramatically, in some cases by as much as 90%. 

At the same time, ships already committed to the region began to create downstream problems. Vessels could not complete rotations. Cargo could not reach intended ports. Services started to break down beyond the Gulf itself as schedules unravelled. 

Thousands of vessels and tens of thousands of crew were effectively stranded or delayed. Even after ceasefire discussions began, traffic did not return to normal. Operators faced unclear rules of passage, security risks, and the possibility of further escalation. 

Flows did not stop completely. Some smaller or approved operators continued to move through the Strait, while larger carriers held back. 

This is what disruption looks like in practice. Not a clean break, but a system fragmenting in real time.

The mistake in how we war-game

Most planning frameworks would treat this as a single event.

The Strait closes. Flows stop. What do we do?

But that misses the sequence that actually matters. Long before the Strait was effectively closed, operators had already:

• suspended services
• rerouted vessels
• reprioritised cargo
• revised schedules
• adjusted supply and demand assumptions

And those decisions shaped the outcome.

By the time the chokepoint became the headline, the system had already been reconfigured.

Where the real pressure sits

The important question is not whether a chokepoint closes, but how quickly the system starts to behave as if it might.

In the Hormuz case, pressure showed up in three places at once.

First, movement became unreliable. Ships slowed, diverted, or stopped entirely. Transit times stretched and became harder to predict.

Second, networks lost rhythm. When vessels could not exit the Gulf, they disrupted global service loops. Delays did not stay local. They cascaded into other routes and regions.

Third, participants began to diverge. Some operators continued to move, others paused entirely. That created uneven capacity and unpredictable availability.

None of these required a formal closure. They emerged as soon as disruption became credible. This is where most of the operational damage is done.

Decision compression in practice

What follows is not just higher cost or slower movement, but a steady narrowing of options.

In more stable conditions, decisions about sourcing, allocation and inventory can be taken with time and flexibility. Under pressure, that space contracts quickly. In the Hormuz disruption, the strain showed up further upstream, in decisions taken well before any visible break in flows.

Producers had to weigh whether to continue loading cargoes into an increasingly uncertain transit environment or hold volumes back. Traders began to reassess positions as pricing, timing and delivery risk pulled apart. Refiners and buyers were forced to choose between drawing down inventories, delaying purchases, or securing supply at higher cost under tighter conditions.

These decisions do not wait. They move as soon as disruption becomes credible.

At the same time, the system offers little room to adjust. There is no viable alternative route for volumes leaving the Gulf at scale, while pipeline capacity is limited and storage within the region is finite. That shifts the problem away from rerouting and towards timing and allocation.

As flows slow or stall, cargoes begin to bunch, delivery windows slip, and availability becomes uneven across markets. Some buyers receive supply while others are left short. Prices respond, but physical constraints increasingly shape outcomes.

By the time disruption becomes visible at scale, most of the meaningful decisions have already been taken, and they have been taken under pressure.

What this means for war-gaming

If this is how disruption actually unfolds, then war-gaming needs to change.

Starting with the event is not useful, because the event is the outcome of earlier decisions.

A more useful approach is to follow the sequence as operators experience it.

• Where does behaviour change first?
• When does that change become binding?
• What decisions are forced at that point?
• And what options disappear as a result?

This is less about predicting the exact path of disruption and more about understanding how quickly flexibility is lost.

A different way to think about chokepoints

Maritime chokepoints do not operate as on-off switches. They operate as pressure points.

As pressure builds, the system adapts. Routes shift, capacity moves, and decisions are made earlier than planned. Those adaptations then shape the impact of any eventual disruption.

The Strait of Hormuz has shown this clearly. Flows did not simply stop. They thinned, stalled, diverted, and fragmented. And in doing so, they forced decisions across supply chains well before any formal closure.

The strategic takeaway

The critical window is the period when the system is still functioning, but under visible strain. That is when decisions remain open, even if only briefly.

Once those decisions are forced, the outcome is largely set.

The role of war-gaming is not to model the collapse. It is to understand when you run out of room to act, and what you will do before that happens.