Ukraine halted the flow of Russian gas to several European countries on New Year’s Day, bringing an end to Moscow’s decades-long dominance over Europe’s energy markets.

Russia’s state-owned energy giant Gazprom confirmed gas exports to Europe via Ukraine stopped at around 8 a.m. local time (5 a.m. London time) on Wednesday.

The widely expected move marks the end of a five-year transit agreement between Russia and Ukraine, with neither side willing to strike a new deal amid the ongoing war.

Ukrainian President Volodymyr Zelenskyy said last month that Kyiv was not prepared to prolong the transit of Russian gas, adding: “We will not give the possibility of additional billions to be earned on our blood.”

Russia, which has transported gas to Europe via Ukrainian pipelines since 1991, says European Union countries will suffer the most from the supply shift. Moscow can still send gas via the TurkStream pipeline, which links Russia with Hungary, Serbia and Turkey.

Ukraine will lose up to $1 billion a year in transit fees from Russia due to the stoppage, according to Reuters, while Gazprom is poised to lose close to $5 billion in gas sales.

The European Commission, the EU’s executive arm, said it had been working with EU member states most impacted by the end of the gas transit agreement to ensure the entire 27-nation bloc was prepared for such a scenario.

Slovakia, Austria and Moldova are among the countries most at risk from the stoppage. They were most dependent on transit volumes of Russian gas in 2023, according to Rystad Energy, with Slovakia importing roughly 3.2 billion cubic meters that year, Austria receiving 5.7 billion cubic meters and Moldova getting 2 billion cubic meters.

Austria has insisted it is well prepared for the stoppage, but others were much more concerned.

Slovakia’s Prime Minister Robert Fico warned that Ukraine’s termination of the gas transit agreement would have a “drastic” impact on the EU, without harming Russia.

Fico also threatened to cut electricity supplies to neighboring Ukraine. The prime minister, a vocal critic of the EU’s support for Ukraine in the ongoing war, made a surprise visit to Moscow for talks with Russian President Vladimir Putin shortly before Christmas.

Moldova, which is not a member of the EU, declared a 60-day state of emergency last month over energy security fears.

A total of 56 lawmakers of Moldova’s 101-seat parliament voted in favor of a nationwide state of emergency, which the government said at the time would allow the country to apply a series of measures to prevent and mitigate the threat of insufficient energy resources.

Ukrainian Energy Minister Herman Galushchenko described the cessation of Russian gas flows via Ukraine as a “historic event.”

“Russia is losing markets, it will suffer financial losses,” Galushchenko said via Telegram on Jan. 1, according to a Google translation.

“Europe has already decided to abandon Russian gas. And the European initiative Repower EU provides for exactly what Ukraine has done today,” he added.

Separately, Polish Foreign Minister Radek Sikorski hailed the development as a political victory, accusing Russia’s Putin of having tried to “blackmail Eastern Europe with the threat of cutting off gas supplies.”

The latest data compiled by industry group Gas Infrastructure Europe shows the EU’s gas storage facilities are around 73% full. In Germany, Europe’s biggest economy and largest gas consumer, inventories are currently at nearly 80%.

“Without Azerbaijan or another third party transiting the gas following a swap deal with Russia, the EU will require about 7.2 [billion cubic meters] of gas to be sourced from the LNG market,” Christoph Halser, gas and LNG analyst at Rystad Energy, said in a research note.

“Terminals in Poland, Germany, Lithuania and Italy could forward these volumes to the most affected counties, such as Slovakia and Austria.”

The front-month gas price at the Dutch TTF hub, a European benchmark for natural gas trading, was last seen up 1.2% at 49.49 euros ($51.1) per megawatt-hour on Thursday, according to New York’s Intercontinental Exchange.

Eurasia Group’s Gloystein said gas price moves over the coming months would likely hinge on political developments in the Russia-Ukraine war and remaining winter weather conditions.

“On the political front, there are ongoing talks between some EU members (e.g. Slovakia, where many of Ukraine’s pipelines enter the EU), Russia, and Ukraine to find a compromise that may allow for some resumption of supplies. However, there has been no progress during negotiations around the turn of the year,” Gloystein said.

“On the weather front, expectations are currently for above average temperatures for the remainder of Europe’s winter, which implies the impact of the cuts will be limited,” he added.