AsiaPac Sea Lanes

Why this matters

Trade is usually counted in dollars. The thing that can be stopped is counted in ships. A defence argument conducted in platforms misses where the decision is actually made: three sea lanes have been contested in three years, and none was restored by force alone. Hormuz traffic fell by more than eighty per cent within forty-eight hours of the strikes of February 2026, before a mine was laid. Red Sea transits fell by about ninety per cent with a United States carrier group present, and remained some sixty per cent below pre-crisis levels months after the last attack. Shipowners and underwriters made those calls, not admirals. The insurance market disputes part of that account, holding that safety rather than availability of cover drove the decision. Either way, the decision was commercial.

The traffic

The numbers below are bulk vessel movements — crude oil, refined product, gas, coal, iron ore and soybeans — derived from published annual tonnages divided by a typical cargo parcel for each trade. They are the measure of what a closed lane actually stops.

Sources. Crude oil, refined product, liquefied gas, iron ore and soybeans are taken from UN COMTRADE by commodity code; coal from national import statistics. The method is set out, and calibrated against a port that counts ships, in the data memo.

What is at stake when a lane closes

Australia stops first. It imports about ninety per cent of its refined product, holds reserves measured in weeks, and has two refineries left from eight in 2005. Medicines run above ninety per cent imported. Fertiliser is imported, and a missed season is a missed harvest. Nothing in that list can be substituted at short notice, and none of it is manufactured here.

The region stops with it. Japan, South Korea, Taiwan and the Philippines live on what they bring in. Indonesia and Australia live on what they send out. China is the most sea-dependent economy of all, taking more bulk tonnage across more water than any other, which is precisely why a blockade strategy cuts both ways.

And it does not end when the shooting stops. Iran is the working example. Major combat operations began in February 2026; six months later, after an aerial campaign to reopen the strait, a naval blockade, escorted convoys and negotiations, commercial ships were still being struck. The kinetic phase ends. The siege does not.

The unwinnable war

Follow the traffic and the conclusion is arithmetic rather than opinion. Read the chart once and it looks like fifteen economies with fifteen exposures. Read it twice and it is one system counted from both ends: Australia’s 417 iron ore cargoes a month are China’s 572 arriving, and Australia’s crude leaves for Singapore, Korea and Malaysia and returns as part of the refined product in Australia’s own import column. A conflict that closes those lanes takes the aggressor’s economy down with the target’s, and takes the bystanders with both. Traffic returns to a contested lane on a commercial clock, not a naval one: the decision to sail is made by owners and underwriters, and confidence came back to the Red Sea over months, not weeks, long after the last attack. A fleet can escort. It cannot make an underwriter write a policy or a master sail.

For a country holding weeks of fuel at the far end of those lanes, the question is not who would win. It is how long Australia lasts while the question is being settled. A blockade here is not a strategy that might fail. It closes on the party executing it at about the same speed as on the target, and faster than the fleet conducting it could be assembled. The memos below set out the record: how lanes close, what closes with them, what a siege does to a country that cannot feed or fuel itself, and what would have to be built for the answer to be different.