When Washington leans on Chinese buyers of Iranian oil, the real question is not where Beijing will source its fuel. China can increase imports from Russia, from Saudi Arabia and from other states - oil is a commodity, and commodities have substitutes. The question is far more uncomfortable: can America still determine who part of the Chinese economy is allowed to do business with.

The former head of Israel's Nativ service, Yakov Kedmi, sees exactly here one of China's more serious vulnerabilities. China is by far the largest buyer of Iranian oil, and a large share of that trade runs through private Chinese refineries and trading companies. Those same firms are tied to international banks, insurance, shipping and other parts of the global financial system that Washington can influence.

State companies are shielded, private ones are not

That is where the division that makes this story interesting lies. Large state corporations have far greater political and financial backing from Beijing. Private refineries, traders and shippers have to worry about access to the international market - and a significant part of the trade with Iran passes precisely through them.

American sanctions therefore do not have to force the Chinese state directly to change policy. It is enough for doing business with Iran to become so risky for individual companies that they withdraw on their own. For Beijing that would mean part of its economy can be disciplined by another power's decisions - with no negotiation, no signature, no official concession.

Why this does not stop at Iran

If sanctions, and access to the dollar, to banks and to international markets, prove enough to make private Chinese companies give up Iranian oil, Washington will have shown it still holds serious leverage over the Chinese economy. And a precedent like that need not end with Iran.

Today it is Iranian oil. Tomorrow the same method can be applied to Russian energy, to technology, to finance, or to trade with any state the US wants to isolate economically. Small economies have known this for a long time - when the big players quarrel through banking channels, the bill is not paid by whoever started the argument.

The Chinese answer: build a system that cannot be cut

Kedmi believes China must reduce that dependence, and he describes two directions. The first is developing alternative financial and trade mechanisms that do not depend on American banks, on the dollar, or on infrastructure Washington can control.

The second is much broader - tying as many states as possible to the Chinese economy. The more a country exports to China, the more it depends on Chinese investment or uses the Chinese market, the more expensive it becomes for it to join American pressure on Beijing. So China does not need to turn every state into a political ally. It is enough for the cooperation to become so important that breaking it would do serious economic damage to the other side as well.

That is exactly why Chinese investments, trade agreements and large infrastructure projects in Asia, Africa and the Middle East carry a value that far exceeds the immediate profit. Economic interdependence becomes political protection.

The Balkans have long experience of being a small link in somebody else's chain, and they know well what it looks like when a large partner offers you access and the bill later arrives in the form of a vote. The question everyone here ought to be asking themselves is simple: when Washington and Beijing one day start demanding a side, how much of our economy is already tied to the answer?