Russian President Vladimir Putin has made a decisive move.

After months of threats, the Kremlin cut off gas supplies to two European Union nations Wednesday and warned others could be next.  

The long-feared move against the continent’s energy supply marks a dramatic escalation of Moscow’s bid to weaken the collective resolve of Ukraine’s allies as they send growing numbers of weapons to help Kyiv fight.

NBC News looks at why Russia is doing this, how significant it might be for the war in Ukraine and the West’s growing involvement.

Russian state-controlled energy giant Gazprom announced Wednesday it had halted gas supplies to Bulgaria and Poland for failing to pay for gas in rubles, something Putin had demanded last month in response to tough sanctions imposed by the West on Russia over its invasion of Ukraine. European buyers condemned Putin’s demand, saying it violated existing contracts with payments usually agreed on in dollars or euros, and called into question Russia’s reliability as a supplier.

It took the Kremlin nearly a month to make good on its promise to cut off gas supply to those who didn’t abide by Putin’s instructions. 

Russia is one of the world’s largest producers of petroleum and natural gas, and Europe is heavily reliant on imports from Russia for its energy supply. “In 2021, the European Union imported 155 billion cubic metres of natural gas from Russia, accounting for around 45% of EU gas imports and close to 40% of its total gas consumption,” according to a recent report from the International Energy Agency. 

Meanwhile, Bulgaria imported more than 70 percent of its natural gas from Russia in 2020, E.U. data showed. In the same year, Poland relied on Russia for around 45 percent of its natural gas.

That dependence is one of the few remaining cards in Putin’s hand to fight back against the West’s growing military support for Ukraine and sanctions that have largely cut off Moscow financially from the rest of the world. 

Notably, the decision to cut off supplies to Poland and Bulgaria came the day after the United States and its allies gathered in Germany to pledge more heavy weapons for Ukraine as it steels its defenses for what could be a decisive battle in the eastern Donbas region. 

A billboard reads “Nie karm Putina,” which translates to “Do not feed Putin,” in Warsaw, Poland, on Monday.Metin Atkas / Anadolu Agency via Getty Images

Russia earlier this week angrily labeled this military aid akin to the West fighting a “proxy war” against it, warning of the dangers of World War III and nuclear conflict. It has also said it is striking batches of weapons and supplies in Ukraine from the air. 

But clearly Putin felt this was not going to get the job done.

“The Kremlin sees curtailment of gas supplies to Europe as a tool to break the consensus in the E.U. and NATO to give Ukraine the weapons it needs to bring the war to a successful end,” said John Lough, an associate fellow at London’s Chatham House think tank. “We are now seeing a steady widening of the war as Western countries become more involved in reinforcing Ukraine’s defenses. Moscow is likely to expand the use of its gas [as a] weapon in response.” 

The announcement also put an end, once and for all, to the idea that selling gas to Europe is a purely business transaction with no political ramifications, said Jonathan Eyal of the Royal United Services Institute, a London-based defense think tank. 

“This is clearly Moscow’s use of a political weapon,” he said.  

Fatih Birol, the executive director of the Paris-based International Energy Agency, called Russia’s move the “weaponization of energy supplies.”

Europe is already facing spiking energy prices that have been made worse by Russia’s invasion of Ukraine, leaving many consumers across the continent worried and politicians under pressure to alleviate the crisis.

Europe’s dependence on Russian energy has been a contentious debate topic, with Russian oil and gas continuing to pour into the continent and payments flowing back to Moscow, even as its bombs rained down on Ukraine. The U.S. announced a ban on Russian energy imports last month, but some of its allies that rely heavily on Russia for energy, like Germany, have been reluctant to follow suit given the economic disruption it would cause.

Kyiv has been urging its international partners for weeks to impose a global ban on Russian gas and oil to stop fueling Putin’s war machine, with Ukrainian President Volodymyr Zelenskyy accusing European countries that are still buying Russian oil of “earning their money in other people’s blood.”

European officials held emergency gas talks Wednesday, with European Commission President Ursula von der Leyen denouncing Russia’s move as an attempt “to use gas as an instrument of blackmail.” She sought to reassure customers across the continent that the bloc has been preparing for such a scenario. 

“We have been working to ensure alternative deliveries and the best possible storage levels across the EU,” von der Leyen said in a statement, without providing more detail.

“We will also continue working with international partners to secure alternative flows,” she added, also without specifying. 

Von der Leyen’s words are not just a hollow attempt to counter the Kremlin’s move, Eyal said.  

Even before the war erupted in Ukraine, the European Commission held internal discussions about what it could do if the worst were to happen and its energy supplies were threatened by Moscow. Emergency contingency plans were put in place, and countries were advised to keep emergency stocks stored away, he said. 

“So for instance, Poland has about 81 percent of its current storage capacity in store,” Eyal said, “which is a very good position to be in, because, remember, this is coming to the summer in Europe; our consumption goes down anyway because heating requirements go down.”

While Europe can probably keep its head above water for now, the real test will come in the fall, when cold weather returns and consumption shoots up.

“But I would say that for the moment, the idea that we can do it, we can put up with, it’s correct, not just propaganda,” he said. 

Shortly after Gazprom’s announcement Wednesday, Russia’s top lawmaker, Vyacheslav Volodin, said the state-run company had made the right decision and that Moscow should do the same with other “unfriendly” countries, signaling the Kremlin might not stop at cutting off supplies to Poland and Bulgaria.

This was followed by a warning from Kremlin spokesman Dmitry Peskov, who cautioned that other European countries may see the taps turned off if they refuse to pay for gas in rubles by the time payment is due. 

Peskov rejected the accusation that Russia was using gas supplies to blackmail the continent, instead saying the refusal to abide by Moscow’s demands reflects a Western desire to “punish our country at all costs, even to the detriment of their own taxpayers, gas consumers, producers and so on.”

Lough, of Chatham House, said: “It’s a warning, in particular, to Germany that its gas supplies are not safe and coincides with Berlin’s decision to sharply increase its military support for Ukraine, including the delivery of heavy weapons.”

Compressor station for Russian natural gasThe compressor station in Mallnow near the German-Polish border mainly receives Russian natural gas.Patrick Pleul / Picture Alliance via Getty Images

Germany depends on Russia for about one-third of total energy consumption. The country announced its first delivery of heavy weapons to Ukraine on Tuesday after weeks of pressure at home and abroad. 

Eyal said there was no question the choice of the two countries was deliberate.

Poland, the most vocally anti-Russian E.U. nation, has been a hub for Western weapons supplies and humanitarian aid flowing into neighboring Ukraine as well as millions of refugees racing out. Bulgaria has also backed Ukraine’s cause, and it is one of the continent’s most economically vulnerable nations and heavily dependent on Russian gas.

“The idea there is to try to break European Union solidarity,” Eyal said.

The Gazprom announcement marks the opening of another battlefront for Russia, Eyal said, and it’s unclear whether Putin will have any more success here than he has so far in Ukraine.

While Europe’s dependence on Russian energy has given the Kremlin a potential pressure point to exploit, that reliance works both ways.

“The Russians are behaving as though we don’t care — as in, you are the beggar and I am the one to decide,” he said. “Of course, deep down they must know that this is not the case because what will happen is that as the deliveries diminish and Europe diversifies its resources, it’s highly unlikely to return to a dependency on Russia.” 

That’s a problem for Moscow, he said, because while demand for natural gas is going to continue to be high in the world, getting new customers is easier said than done.

The delivery of gas into Europe was comparatively cheap for the Russians because it was done through existing pipelines built many decades ago, Eyal said. 

“So Mr. Putin now says, ‘If you don’t want my stuff, I will send it to China or to other Asian countries.’ Broadly speaking, he is right. But the devil is in the detail,” he added. “Diversifying that customer base will be an expensive operation for the Russians precisely when they don’t have the cash.”

Asked whether Russia was ready for the budget losses it could sustain if it cuts off more countries, Peskov said that “all risks have been assessed and the necessary measures have been taken.”