Sanctions were supposed to crush the Russian ruble. So why did it just hit a 2-month high?

Western sanctions have devastated Russia's economy since the war in Ukraine started, and for a while, the ruble was also hit hard, losing roughly 20% of its value in the first few weeks following the invasion.

Since then, the currency has largely recovered, all but undoing the losses it suffered as a result of the war and subsequent sanctions. The appreciation has surprised experts who predicted the ruble would continue to fall, barring a ceasefire in Ukraine.

After all, the Russian economy is expected to contract by as much as 15% this year, according to the Institute of International Finance. Ratings agencies have also downgraded Russian debt to junk status, arguing the country may be headed for "imminent" default. That kind of pessimism should, in normal circumstances, lead to a depreciating currency—but the ruble has proved to be resilient.

U.S. Secretary of State Antony Blinken told NBC's "Meet the Press" on Sunday that Russian "manipulation" was the main cause of the ruble's recent rebound after the Russian government restricted its citizens from transferring money abroad.

"People are being prevented from unloading rubles. That's artificially propping up the value. That's not sustainable. So I think you're going to see that change," Blinken said, adding that he is working every day to tighten sanctions and close loopholes that have allowed the ruble to appreciate.

From raising its benchmark interest rate to forcing exporters to swap 80% of their foreign currency revenues for rubles, Russia's central bank has done everything it can to prop up the rubles' value since the Ukraine invasion began, but it's more than just manipulation that's supporting the currency's value.

It all comes down to oil and natural gas

One of the most potent tactics Russia has used to buoy its currency is demanding payments for oil and gas exports in rubles.

While many European leaders have balked at the request and continue to pay in either euros or dollars, other countries have been eager to gobble up Russian energy exports at a discount. India, for example, has dramatically increased its Russian oil imports.

"Energy security [comes] first. If the fuel is available at a discount, why shouldn't [we] buy it?" India's finance minister, Nirmala Sitharaman, said at a CNBC event on Friday. "We have started buying…[and] have received quite a number of barrels. This will continue."

Dr. Alexander Mihailov, an associate professor of economics at the University of Reading, in the UK, told Fortune that politicians should listen to economists and immediately stop importing Russian commodities. If they do, he argues the ruble would rapidly lose value, leading to devastating effects on the Russian economy.