An additional premium negotiated voyage by voyage for a vessel's passage through a war zone, revisable in near real time.
The marine war risk premium does not insure a stable hazard, it publishes a price that continuously reflects a zone's danger. Negotiated by voyage and by endorsement, backed by seven-day cancellable covers, it can be multiplied threefold or fourfold within days of an attack. Its true economic role is that of a signal, and a few well-aimed attacks are enough to lift it to the point where passage ceases to be economic, making it the instrument of a de facto blockade.
After two Greek bulk carriers sank in July 2025, the Red Sea war risk premium rose from around 0.3% to nearly 1% of hull value.
surprime de guerre, additional war risk premium