The ultimate sanction against Russia for invading Ukraine is an embargo on its sales of oil and gas. Impounding the yachts of billionaire oligarchs is incidental to the true source of financing for Vladimir Putin’s war – energy exports.

Last Friday, as rockets rained down on civilian areas, Shell stepped in to the market to buy a substantial quantity of Russian oil at a heavily discounted price. This was not in breach of the sanctions because they do not cover energy sales.

Such was the obloquy heaped on Shell that it subsequently pledged to give any profits to a relief fund for Ukrainian refugees. The company said that, while it was appalled by the events in Ukraine, “we currently purchase it … to ensure that we continue the production of essential fuels and products that people and businesses rely on every day.” Herein lies the conundrum. People in the West are horrified by what is going on in Ukraine but how much disruption to their own lives are they prepared to put up with to demonstrate their concern?

Shell was buying the oil to meet consumer demand in the absence of any other immediately available sources. It may be possible to find alternatives but it will take time, assuming other producers are ready to play ball. An embargo on Russian oil would have a massive knock-on impact on the global economy, not just Russia’s, as was apparent from the fall in global stock markets.

To a great extent a de facto embargo is already in place since traders are largely shunning Russian crude. Shell bought at a heavily discounted price because the producers are struggling to offload it. As storage sites fill up, Russia will be forced to cut production with potentially calamitous consequences for its industry.

On the markets, the price of a barrel is now at a 10-year high, which means bonanza revenues for Russia if it could sell the oil at spot prices. An embargo would make any such purchases unlawful and seriously harm Putin even if he were able to sell some to China. But there can be no pretence that it will not damage Western economies, though America is much less exposed than Europe, where there is little appetite for an embargo as was clear at the No 10 summit yesterday.

The added danger is that such a move reinforces Putin’s domestic narrative that the West has ganged up on Russia. Death by a thousand cuts might be a better option.