Since the US and its allies stopped buying Russia's oil, there has been little indication that the measure is inflicting the kind of pain that might cause President Vladimir Putin to rethink his war in Ukraine. The sanctions have softened the blow by bringing enough revenue to stave off the economic collapse, and a surge in prices has softened the blow.
Putin's adversaries are weighing a new idea: Make Russia sell its oil so cheaply that it can no longer afford to wage war.
What is being proposed?
The US, the UK and Canada have announced that they will ban Russian oil while the EU plans to ban Russian crude by December and fuels by early next year. In a further step, US Treasury Secretary Janet Yellen is backing a proposal to allow nations that abstained from sanctions to keep buying oil but slash Moscow's profits on those sales.
A group of Seven G 7 nations were said to be discussing a mechanism that would allow the transportation of Russian crude and petroleum products sold below an agreed price threshold, to be enforced by imposing restrictions on insurance and shipping.
Around 95 per cent of the world's oil tanker fleet is covered by the International Group of Protection Indemnity Clubs in London and some firms in continental Europe. Western governments might try to impose a price cap by telling buyers they can keep using that insurance, as long as they agree not to pay more than a certain price for oil on board.
Putin says Western nations are suffering more than Russia because of the economic penalties they imposed over his invasion of Ukraine. Excluding Russian commodity exports has helped his government weather the sanctions because of the soaring prices of the Russian commodity exports.
Capping prices at a level that is closer to the cost of production would give a blow to Moscow's finances while still ensuring that energy flows to where it is needed. As Russia is one of the world's biggest oil suppliers, a price cap could relieve inflationary pressure that is causing economic hardship across the world.
Some European officials have been wary of the idea as it would require the EU to reopen the legal text of its latest sanctions package, which took weeks to approve and had to overcome significant hurdles because of the sanctions that require unanimity among the bloc's 27 nations.
If the allies do not agree on a price cap but it fails to hold, it would hand a symbolic victory to Putin. There are plenty of ways that it could fail: There is no guarantee that Russia would ship oil at capped prices, especially if the cap is close to production cost.
Some EU countries that don't meet its payment demands have already shown that it is willing to withhold natural gas supply. The Kremlin may believe that holding its oil off the market would do more damage to the economies of Europe and North America than to its own.