Clara Ferreira Marques is a Bloomberg Opinion columnist covering foreign affairs and climate.

Economic sanctions have a bad reputation as a weapon that promises plenty — “something more tremendous than war,” as US President Woodrow Wilson put it in 1919 — but delivers comparatively little.

Unprecedented measures aimed at isolating Russia have not stopped the fighting in Ukraine, or forced President Vladimir Putin out. The ruble has recovered and the cost of squeezing Moscow is rising. But that doesn't mean sanctions aren't working, much less that a solution that protects Ukraine's interests and global security is possible without continued, and increasing, pressure.

It's certainly the case that economic sanctions have a patchy record when it comes to altering behaviour. Even the best-known efforts, like South Africa during apartheid, were not clear-cut successes.

Cuba's regime is still in place, as is Venezuela's, and even more targeted sanctions, say against Myanmar's junta, haven't had the intended bite.

Worse, the campaign to curb Saddam Hussein in Iraq showed just how difficult it is to punish dictators who are willing to let their population starve for the cause.

This time, there's also the fact that the target is one of the world's largest hydrocarbon and grain exporters, meaning restrictions result in painfully higher prices for consumers elsewhere.

But as we grind through the fourth month of this conflict, it's vital to recall that the aim of the sanctions effort was to erode Putin's ability to wage his war of conquest in Ukraine — and that is happening. Capital controls are supporting the ruble, but even high energy prices won't stop economic contraction in the near term and, crucially, stagnation thereafter.

The central bank is run by capable technocrats but now has to plan for “structural transformation,” a euphemism that ultimately describes the embrace of autarky and isolation, in a country running short of everything from buttons and bleaching chemicals for paper to spare parts for passenger jets.

Success — by which we should mean a solution that protects Ukraine's sovereignty and interests — will require more. More efforts to build resilience among allied governments and populations, combined with realism on timing and cost, because freedom is not free and all of this takes time.

The EU's oil embargo, for example, does not even kick in for months, and because of inventories, not all trade restrictions are yet hitting home. It will also mean more efforts to tighten enforcement, close loopholes and edge towards further energy restrictions, even tariffs to cut off the Kremlin's revenues faster. And it means more weapons and more diplomacy — because sanctions don't work alone.

The alternative is to pause and simply allow the current position to simmer. That's tempting, given the impact of measures taken to date is only beginning to become clear and costlier fuel hurts.

But time is on Russia's side. It allows the economy to adjust and softens the blow from punitive measures. It will encourage Moscow to prolong the fighting, when there's an opportunity to demonstrate resolve instead.

Most damning, it would suggest Putin is right to think that whatever their high-minded ideals, Europe, the US and their allies, buckle under the pressure of electoral cycles. Others will learn from that.

Maria Shagina, who researches economic sanctions and strategy at the International Institute for Strategic Studies in Berlin, argues that a pause allows both the deterrent effect and the shock value of sanctions to fade, raising the risk that allies bring to the table neither enough weapons to Ukraine, nor enough economic pain for Russia.

That increases the chance that fatigue will set in and weakens Kyiv's negotiating position.

Russia's economic fortress has helped it weather sanctions better than it might have otherwise and, though not all defences worked, policy makers have contained the worst. A stronger ruble, thanks to capital controls and mandatory conversion of export revenue, is keeping price increases in check.

And, of course, Moscow is still raking in cash from energy exports. The Kremlin is making the best of this propaganda win. But look closer, and Russia is hurting. Inflation is slowing not only because of central bank actions, but because demand is paltry and confidence weak.

Low unemployment, which Putin has highlighted, reflects the weight of state enterprises and a willingness to cut hours and wages before jobs, rather than a thriving economy.

Then there's the drop in imports, rippling through a system that remains highly dependent on overseas components. Putin will no doubt keep putting the war machine first, but it's clear that while Russia can prop up the currency and prevent bank runs, it can't as easily shield itself from trade sanctions by finding alternative markets.

A central bank study published in April found two-thirds of surveyed companies had experienced import problems, and sanctions have gummed up everything from cars to agriculture - compounded by the voluntary exodus of private companies. With supply disrupted, car sales fell more than 80% in May.

Even tank manufacturing giant Uralvagonzavod has reportedly halted production, while the military is scrambling to deal with chip shortages as sales from major producers are suspended. Meanwhile China, Russia's no-limits partner, is in fact setting clear limits on how far it will go. Russia's economy may not be crashing, but it's firmly in reverse.

Dictators have higher pain thresholds than democratic leaders, that's clear. All the more reason to keep up pressure, making it harder for Russia to reshape and regroup, instead of allowing the regime time it can use.

Two further steps are vital. One is to do more to prepare allied governments and their voters for a conflict that will not be resolved swiftly. Any hurried compromise will benefit neither Ukraine's security interests, nor those of most of the rest of the world. It will not be easy to convince Europeans or Americans to accept some discomfort — but fiscal support and clear aims can help.

Then it is time to introduce some level of conditionality into existing and future measures — to explicitly demonstrate that Moscow does not have to be locked into confrontation. As IISS's Shagina put it, this is the way to maximize the potential of sanctions and of Western leverage.

Yes, there are risks. Russia is a nuclear power that does not want to be backed into a corner, and its economy will, eventually, adapt to a reduced reality. There could be counter-sanctions, and unintended consequences.

But a lack of resolve is more dangerous still. This war can only end at the negotiating table — and there, lasting peace will depend both on strengthening Ukraine's hand and on weakening Russia's.

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