Evil exists. It sits in the Kremlin consumed by resentment and lust for power. It marches into a country whose crime was to dream of freedom and democracy. How is such evil to be defeated? Might economic sanctions, combined with the resistance of the Ukrainian people, force Vladimir Putin into retreat? Or might they even lead to his overthrow? Alternatively, might he risk escalation up to use of nuclear weapons?

Beyond doubt, the sanctions the west has used are powerful. Putin has even called them “akin to an act of war”. Russia has been largely cut out of the global financial system and more than half of its foreign reserves have been rendered useless. Western businesses are frightened of continuing to engage with Russia, for reputational and prudential reasons. Neil Shearing, chief economist of Capital Economics, forecasts a peak-to-trough fall in gross domestic product of 8 per cent, followed by a lengthy period of stagnation. The jump in the central bank’s interest rate to 20 per cent will on its own be costly. Shearing may well be too optimistic. (See charts.)

Restrictions on energy exports are an obvious next step, as the Biden administration argues, against German opposition. It is, to say the least, objectionable that the high energy prices caused by Putin’s crimes also finance them. The Ukrainian economist Oleg Ustenko has argued strongly for such a boycott. Harvard’s Ricardo Hausmann proposes a neat alternative: a tax of 90 per cent on Russia’s exports of oil and gas. Since supply elasticity is low, he argues, the costs would fall on Russian producers, not western consumers, and so scarcity rents would also be transferred to the latter.