There is no single test of whether a strait is open. Whether the channel is physically blocked, whether mines have been cleared, and whether owners will actually send ships are separate questions. Washington has said mines were cleared; Tehran says the closure stands.

What governs transits in practice is war-risk insurance. Once premiums exceed a certain share of hull value, the economics of a voyage disappear, and owners divert regardless of physical passability. Gulf war-risk rates have been repriced repeatedly in recent months.

Diversion costs time and fuel. For crude and LNG cargoes bound from the Middle East to East Asia the alternatives are limited, so fewer transits translate directly into later arrivals. Refiners and power utilities in Korea, Japan and Taiwan have responded by holding more days of stock.

For traders in Chinese communities the episode appears as a contracts problem: penalty clauses for late delivery, who bears surcharges, and confirmation of insurance coverage are the recurring items.

Transit counts are compiled from automatic identification system data and published weekly. The next release will indicate which account is closer to the water.