International Trade

The International Trade system is an inter-country trade clearing engine that computes trade affinity between every pair of countries each turn. Affinity determines how much trade flows between countries and is modified by free trade agreements, shared organization blocs, tariffs, and ministerial embargoes.

Core concept: trade affinity

Every country pair has a trade affinity value that represents how much trade flows between them. Affinity starts at a base of 1 and is then multiplied (or reduced) by several modifiers:

1. FTA affinity bonus: if the pair is covered by an active free trade agreement
2. Bloc affinity bonus: if both countries share membership in the same international organization
3. Tariff drag: a reduction based on the effective tariff rate between the pair
4. Ministerial embargo: a hard zero if one country has embargoed the other

The final affinity is the product of all applicable modifiers.

Modifiers

FTA affinity bonus

When two countries are covered by an active free trade agreement (passed through an international organization), their trade affinity is multiplied by 1.6×.

This is the single largest trade modifier in the system and makes FTAs the most impactful diplomatic tool for boosting bilateral trade.

Bloc affinity bonus

When two countries share membership in the same international organization, their trade affinity is multiplied by 1.25×.

This bonus stacks with the FTA bonus. Two countries that are both in the EU and have an active FTA receive a combined 1.6 × 1.25 = 2.0× affinity multiplier.

Tariff drag

Tariffs reduce trade affinity. The drag formula is:

At common tariff rates:

At a 20% tariff, drag is approximately 0.625, meaning trade affinity is reduced by 37.5%. High tariffs make bilateral trade dramatically less efficient.

Note: Tariff drag is computed from the effective tariff rate, which is the sum of all applicable tariff layers (economy-wide, sector, origin-country, corporation-specific). See Tariffs for how the effective rate is calculated. Active FTAs can override the effective rate to zero for covered partners, eliminating drag entirely.

Ministerial embargo

A ministerial embargo is a hard block on trade between two countries. When active, trade affinity between the embargoing country and the target is set to zero: no trade flows regardless of other modifiers.

The iron curtain

In the Cold War eras the Soviet bloc trades behind a wall. Trade between a curtained country and the open world is zero in both directions; trade within the curtain (the Comecon market) and within the open world is unaffected. No FTA, bloc bonus or tariff setting reaches across it. The curtain is decided per era by history rather than by any minister: Yugoslavia broke with Moscow before the 1953 world opens and trades with the West, so it sits outside the curtain (and is cut off from the bloc's internal market) while keeping its planned economy at home.

Autonomous governments

Countries nobody plays run their own trade policy. An autonomous government can table trade agreements, apply targeted tariff bills against a rival, and impose bounded ministerial embargoes, with cooldowns per country pair and a limit set by how much it actually depends on that partner's trade. Expect a hostile relationship to show up on your tariff and embargo screens even when no player is behind it.

IPF convergence

The trade clearing engine uses iterative proportional fitting (IPF), a method that repeatedly adjusts trade numbers in small steps until every country's imports and exports line up, to balance trade flows across all country pairs. The engine runs 40 iterations, which converges margins to below 0.5%, meaning the result is effectively exact for gameplay purposes.

This ensures that the affinity values produce a self-consistent trade matrix where every country's imports and exports balance correctly.

Ministerial embargoes

Embargoes are the most aggressive trade tool available. They are issued by a cabinet minister and have strict limits:

Rules

• Cost: Each embargo consumes 1 cabinet action to enact.
• Duration: An embargo lasts at most 96 turns (approximately 2 game years), after which it expires automatically.
• Concurrent limit: A single member can have at most 2 active embargoes at any time.
• Cooldown: The 168-turn source-to-target cooldown starts when the embargo is enacted, not when it expires.

Because the maximum embargo lasts 96 turns, a full-duration embargo leaves at least 72 turns before that source can target the same country again.

Affinity calculation summary

The full affinity calculation for a country pair:

Example scenarios

Note the FTA override: even though a 20% tariff is on the books, the FTA collapses the effective tariff to zero for covered partners, so the drag multiplier becomes 1.0 and the full 1.6× FTA bonus applies.

Strategic notes

• FTAs are the strongest trade lever. A 1.6× multiplier dwarfs all other modifiers. Prioritize passing FTAs through international organizations with your key trading partners.
• Bloc membership is cheap affinity. Simply being in the same org as a trading partner gives a 25% boost with no legislation required.
• Tariffs and FTAs interact. An FTA makes tariffs irrelevant for covered partners: they pay zero. Use FTAs to shield partners from your own tariff policy.
• Embargoes are blunt and temporary. They zero trade but expire after 96 turns and trigger a 168-turn cooldown. Use them for targeted pressure, not permanent isolation.
• IPF convergence is exact at 40 iterations. You can trust that the trade matrix is self-consistent: there are no "approximate" affinity values in the final result.

Public API

Trade restrictions are available to bots and dashboards through the public v1 API:

• GET /api/public/v1/trade/tariffs lists active tariff layers and supports imposing-country, target-country, scope, and limit filters.
• GET /api/public/v1/trade/embargoes combines active ministerial, legislative, and organization sanctions. Add includePending=true to include embargo bills still moving through a legislature.
• GET /api/public/v1/trade/flows returns bounded world trade history. Filter by country, commodity, and turn range to chart exports, imports, net balances, and cleared volume.

The restriction routes include their public bill or organization-resolution provenance. They do not expose the character IDs used internally to enact a restriction. Trade-flow history omits raw bilateral matrices and internal reachable market books. See the public API documentation for parameters and response fields.

Related systems

• International Organizations: where FTAs and bloc memberships are established
• Tariffs: how tariff rates are set and how they stack
• National Budget: how tariff revenue feeds into government finances
• Corporations: how trade affinity affects corporate sector margins