MOSCOW — On the morning of Jan. 1, Russia pumped its last cubic meters of natural gas directly to Europe, ending decades of trade that had benefited all sides — and heated homes — through some of the darkest winters of the Cold War and well into the 21st century.

Russia’s invasion of Ukraine unraveled all of that.

After Moscow tampered with the flow to Europe as a response to Western sanctions in 2022, European economies raced to reduce their dependence on Russian gas amid fears they had traded cheap energy at the expense of security.

The Yamal-Europe pipeline through Belarus to Poland soon closed. Two others feeding Germany, Nord Stream and Nord Stream II, were destroyed by saboteurs under still-murky circumstances later that same year. All that was left was a pipeline named Druzhba, Russian for “friendship,” that ran through, of all places, Ukraine — a legacy of a less divided Europe that no longer exists.

Here is what to know about the gas cutoff.

Where is the gas crisis most acute?

For now, the crisis is focused in a region called Transnistria, located on the eastern edge of the former Soviet republic of Moldova. It’s a sliver of territory with a population of some 360,000 bordering Ukraine that declared independence with the breakup of the USSR. It has been under Russian protection, including by Russian peacekeepers, ever since.

Transnistria’s economy has always survived thanks to cheap Russian gas — and its energy-related problems have cascaded since the New Year’s stoppage. There is no heat or hot water for residents. Nearly all factories have stopped operations. Schools and residential buildings have also gone cold — with residents told to dress warmly or gather firewood from nearby forests.

While the region’s key power station has switched from gas to coal to continue service, supplies are limited. Meanwhile, the use of portable electric heaters has overstressed the power grid — with more than a hundred fires reported daily. As a result, the local self-proclaimed authorities have introduced rolling blackouts in increasing increments — hoping to avoid a full blackout.

Why was Ukraine allowing Russia to export gas via its territory, given the war?

Ukraine continued to honor a five-year preinvasion contract to export Russian gas through its territory to central Europe — with Russia’s energy giant Gazprom raking in the proceeds and the Ukrainian government collecting transit fees. That came to an end Jan. 1. Ukrainian President Volodymyr Zelenskyy declared the deal akin to blood money and vowed it wouldn’t continue. Kyiv has celebrated the end of the transit deal as a major blow to Russia’s economy — and its war machine.

“When Putin was presented with the Russian presidency more than 25 years ago, the annual gas transit through Ukraine to Europe totaled more than 130 billion cubic meters,” Zelenskyy wrote on the social platform X. “Today, it equals 0. This is one of Moscow’s biggest defeats.”

Does this mean Europe will freeze this winter?

No. Ukraine had signaled well in advance it had no intention of renewing the transit contract with Moscow so long as the war continued. Most of Europe had already shifted away from Russian gas — or had come up with alternative solutions, including imports of U.S. liquefied natural gas.

But some European countries remain bitter over the end of Russian gas. European Union member Slovakia, in particular, has accused Kyiv of “sabotage” and threatened to punish Ukraine over the loss of its own transit fees from the Russia-Ukraine agreement.

More vulnerable still? Moldova, which has its own ambitions of joining the EU.

Why is Moldova so vulnerable?

Gas exports have long been a tool of Russian influence in Moldova, particularly at moments when the government in the capital Chisinau has pushed a distinctly pro-Western path.

And there are signs of politics once again at play.

Even before the end of the gas transit deal with Ukraine, Russia’s Gazprom said it was suspending exports to Moldova over some $700 million in unpaid gas supplies — a charge Moldova disputes.

And while Moldova had already taken steps to diversify its energy options, notably by importing gas and electricity from neighboring Romania, the breakaway region of Transnistria leaves it exposed on several fronts.

Transnistria’s main power plant still provides electricity to significant parts of the rest of Moldova.

Moldova’s government also openly accuses Russia of “blackmail.” It argues that the Kremlin is hoping an energy crisis, and the accompanying humanitarian fallout in Transnistria, will undermine Moldova’s pro-Western policies when the country holds parliamentary elections later this year. The Kremlin has denied the accusation.

What does Russia say?

Russia’s Gazprom blamed Ukraine for its decision not to renew the transit deal, saying in a statement that it now lacked “the technical and legal means” to provide gas to its customers in Europe. The energy giant also continues to insist Moldova’s outstanding debts make supplying the country by other circuitous routes — such as through a Russian-Turkish pipeline that tunnels under the Black Sea — untenable.

Russia’s Foreign Ministry, however, has been more explicit in promoting a long-running Russian conspiracy theory: that the U.S. had orchestrated the whole thing at Europe and Russia’s expense.

“The main beneficiary of the repartition of the energy market of the Old World is the main sponsor of the Ukrainian crisis — the United States,” Foreign Ministry spokesperson Maria Zakharova wrote on social media.

“Now for the price of American protection, other countries in the once economically successful and independent European Union will be forced to pay.”