Tub-thumping by politicians is not far removed from breast beating by homo sapiens’ close relatives. The drama lies in the sound and fury but effective action does not necessarily follow.

Investors in the oil market may have already come to that conclusion about threats of sanctions against Iran by the US and Europe and some smaller players.

Their response so far has been ambivalent. The price of oil is not far from where it was at the start of the year, despite the sanctions threats. And, on Friday, Bloomberg reported the oil price declined to a six-week low in New York as US supplies climbed and fuel demand tumbled.

There are two possible explanations for the muted reaction of the market.

Tony Twine, the senior economist at Econometrix, says importing countries will find other sources should they join the boycott. And Iran will be able to shift its sales from boycotting countries to non-boycotting countries.

So the overall demand-supply situation won’t change materially.

“It’s a sort of swings-and-roundabouts situation,” Twine says. He points out also that oil can change ownership several times a day and tracing the source of supplies is a difficult business.

Under sanctions before 1994, South Africa was able to export gold through a variety of channels because, unlike Outspan oranges, one bar of gold is identical to another.

Sanctions are always a double-edged sword, which is why many countries are weighing their options over sanctions against Iran.

China, the world’s second-largest crude consumer, not surprisingly, opposes them. So does Iraq.

Reuters reported on Friday that Iraq “could seek a waiver from the US on sanctions on Iran because of its high trade with the neighbouring country and to protect its foreign reserves from penalties”.

China has been called on to use its influence on the intransigent Middle Eastern power. At the heart of the sanctions issue is Iran’s nuclear programme, which western countries and some of Iran’s neighbours see as a threat to peace and stability.

But at this point everything hangs in the balance.

South Africa, which has not yet come out either in support of or in opposition to sanctions, has a big stake in the outcome of the stand-off.

Between January and November last year, South Africa imported R25.8 billion worth of mineral products – the section under which Customs and Excise classifies oil – from Iran. South Africa’s total imports of this category were worth R145bn.

The value of imports from Iran was second only to Saudi Arabia, from which South Africa imported R26.1bn.

The next biggest supplier was Nigeria, which sold R21bn worth of oil to South Africa in the period. Angola followed with R9.7bn worth. A number of other countries, several of them Persian Gulf states, sold smaller amounts.

Twine put the figures in perspective. “Though imports from Iran sound like a lot of oil, it’s only about the size of an average oil spill.”

The US is not just proposing sanctions on Iran’s exports – but also a US travel ban and the freezing of US assets of people and companies that sell technology to Iran. Perhaps the threats will pay off.

Sanctions are less destructive and less costly than warfare. So tub-thumping is a relatively harmless outlet for aggressions that could otherwise end in another round of “shock and awe”.