(CNN) — When President Joe Biden convened nearly a dozen Western leaders by private video conference on Thursday to discuss the war in Ukraine, he was intent upon delivering a key message, sources say: to stay unified in punishing Russia, even as the Kremlin tries to weaponize energy and break Western resolve.

It was at least the second such entreaty to Europe last week to maintain the sanctions pressure on Russia, in the face of skyrocketing energy costs caused by Russia’s invasion and the prospect of a tough winter after the Kremlin shut off gas flows to Europe through a key pipeline. In an op-ed published in the Financial Times on Wednesday, NATO Secretary General Jens Stoltenberg urged citizens to stay the course and continue to support Ukraine, even in the face of “a difficult six months.”

The intensifying messaging campaign underscores a growing wariness in Washington and Brussels that Moscow’s weaponization of oil and gas — its two biggest exports and increasingly the backbone of its economy — could successfully force fissures in what up until now has been a largely united European front opposing Russia’s war in Ukraine.

Sowing that division and wearing down western resolve has been a key priority for Russian President Vladimir Putin, US and Western intelligence officials say — especially as Russia struggles to make any substantial gains on the battlefield against the Western-backed and increasingly well-equipped Ukrainian forces. On Saturday, Ukrainian forces made major gains in the northeastern region of Kharkiv, retaking the key cities of Izium and Kupyansk.

“Putin’s bet is that he’s going to be tougher than the Ukrainians and the Europeans and the Americans, that he can wear down the Ukrainians, strangle their economy, [and that] the Europeans, facing what’s going to be a difficult winter with high energy prices, are going to lose resolve,” CIA Director William Burns said on Thursday.

Europe, including the UK, is already feeling the effects acutely, with energy bills skyrocketing and leaders warning that the continent could face electricity blackouts in winter depending on how low temperatures drop. “The electricity market is no longer a functioning market because there is one actor, Putin, who is systematically trying to destroy it and to manipulate it,” Ursula von der Leyen, president of the European Commission, said in a speech earlier this month.

EU energy ministers are also clashing over a plan being considered to cap the price of Russian gas. Countries, including Hungary, Austria and Slovakia, are wary of such a cap because of the risk that Putin might retaliate by completely severing what remains of the Russian gas flows to those countries.

Putin appeared to threaten as much in a speech last week at the Eastern Economic Forum.

“We will not supply anything at all if it contradicts our interests,” he said. “We will not supply gas, oil, coal, heating oil — we will not supply anything. “We would only have one thing left to do: As in the famous Russian fairy tale, we would let the wolf’s tail freeze.”

White House officials continue to insist that they have seen no visible breaks in the unified front and to some degree have viewed Putin’s actions as both predictable and serving to only steel the resolve of European allies. “If anything, we believe Russia’s actions have actually only increased unity among Europeans,” said one senior US official. “The message that Russia is sending every European is that they are not reliable. So the animosity towards Russia is just increasing.”

But the risk is real, other US officials say, that as electricity costs rise and winter approaches, European publics could turn against the Western strategy of isolating Russia economically.

Russia “definitely want[s] Europeans to be nervous — energy is their biggest tool for turning European publics against the war,” said one source familiar with Western intelligence.

The direct impact on the United States remains negligible, two sources familiar with US and Western government views said, given that the US does not rely at all on Russian energy imports and is actually a major exporter of liquified natural gas— a fact that allowed Biden to pledge in March that the US would send an additional 15 billion cubic meters of LNG to the EU by the end of the year. A combination of market forces, administration facilitation and the lack of destination restrictions has allowed US producers to already hit Biden’s pledge — twice over.

But US officials closely monitored a recent protest against high energy prices in the Czech Republic and have kept a close eye on any signs of growing instability in Europe.

“We’re obviously watching this closely,” White House National Security Council Spokesman John Kirby told CNN. “From our perspective, we still see strong resolve and unity at the leadership level here in the face of the way in which Putin is weaponizing energy. And the President is committed to preserving that unity and that resolve and that strength.”

‘All on hands on deck’ diplomacy

Inside the White House, there has been an all-consuming effort to identify, secure and direct gas supplies to countries who are on the one hand critical to the coalition, and on the other exceedingly vulnerable to Russian efforts leverage its vast energy resources.

“It’s playing into all of our diplomatic engagements,” the senior administration official said “We understand the magnitude. It’s all hands on deck.”

The acute danger of Europe’s vulnerability was laid bare this week. Biden’s meeting with allied leaders came just days after Russia indefinitely shuttered a critical gas pipeline, Nord Stream 1 — and less than a week after tens of thousands gathered in Prague to protest soaring costs.

Gazprom, the operator of the Nord Stream 1 pipeline, cited various technical issues for reducing the flow of its gas over the course of the several months. But earlier this week, Kremlin spokesman Dmitry Peskov told reporters that the gas would not start flowing again until the West lifts its sanctions on Russia.

“Problems with gas supply arose because of the sanctions imposed on our country by Western states, including Germany and Britain,” Peskov said on Monday.

Western intelligence officials have viewed the move as just the latest salvo in Russia’s attempts to weaponize the energy supply and foment political instability.

“Drive up energy prices and sap the domestic support generally, then drive them up further and piss people off enough to create some major political problems,” one US official said in summarizing the general theory. “Oil and natural gas are [Putin’s] hammer.”

The threat of political instability, which US and EU officials view as ripe for foment by right-wing elements across Europe, has long been acknowledged as a threat, but rarely talked about openly. That has changed.

“A few weeks like this and the European economy will just go into a full stop,” Belgium’s Prime Minister Alexander De Croo said in a Bloomberg interview this week. “The risk of that is de-industrialization and severe risk of fundamental social unrest.”

US officials have been working relentlessly to try to prevent that from happening, with President Biden making it a top priority, sources told CNN. As a result, the nearly year-long effort to redirect gas supplies to Europe and reduce its dependency on Russia has helped to rapidly fill storage capacity, redirect orders and infrastructure, and identify policy options and technology to increase efficiency and reduce usage.

The effort has spanned the globe and cut across cabinet officials and agencies, closely coordinated with EU counterparts and with an emergency US-EU energy task force serving as a clearinghouse. European leaders, meanwhile, have engaged in a furious diplomatic and deal-making sprint to capitals around the globe in an urgent push to secure alternatives to the Russian energy that holds a dominant role across the continent.

It’s had a clear effect. Russian gas imports have dropped to 9% from a high of roughly 40% before the war, European Commission President Ursula von der Leyen said earlier this month. Reliance on Russian oil has also fallen precipitously.

Ultimately, however, much will likely depend on the weather, multiple US and Western officials told CNN. If it’s a mild winter, gas storage tank reserves — which have already exceeded benchmarks — may be enough to prevent widespread shortages, according to one official familiar with Western intelligence.

But that’s far from a guarantee, that person said. As EU leaders scramble to adopt new measures to freeze or cap energy prices and deploy billions in new financial assistance and liquidity, the presence of a crisis that could spill into economic calamity is palpable.

“It’s going to hurt for Europe,” this person said. “Let’s see how harsh the winter is.”

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