ATHENS/SKOPJE/BELGRADE, Sept 5 (BalkanView) – Serbia and North Macedonia are joining an expanding north-south natural gas network anchored in Greece, bringing the Western Balkans deeper into a European and U.S.-backed effort to diversify energy supplies and reduce the continent’s remaining dependence on Russian gas.
Natural gas transmission operators signed a new memorandum of understanding in Thessaloniki on Friday to expand the Vertical Gas Corridor to the two Western Balkan countries, following months of technical discussions over integrating their networks.
The move connects an energy-security project initially centred on Greece, Bulgaria and Romania with a much wider chain of countries stretching through Moldova towards Ukraine and, increasingly, into Central Europe.
North Macedonia’s NOMAGAS and Serbia’s Transportgas Srbija had already joined discussions with operators from Greece, Bulgaria, Romania, Moldova, Hungary, Slovakia and Ukraine in Athens in July. The talks examined transmission capacity, interconnection points, infrastructure investments and the timetable needed to integrate the two Balkan systems.
Their entry gives the project a new Western Balkan dimension and could eventually allow gas entering southeastern Europe through Greek LNG terminals or pipelines from Azerbaijan to move across a larger interconnected market.
The implications extend well beyond the two countries.
At stake is an emerging energy axis running from the Aegean northwards at a time when Europe is restructuring a gas system that for decades was largely designed to carry Russian supplies from east to west and north to south.
ALEXANDROUPOLIS BECOMES A GATEWAY
The latest step was symbolically preceded by a visit on Thursday by regional gas transmission operators, including representatives from North Macedonia and Serbia, to the floating LNG terminal at Alexandroupolis in northeastern Greece.
The floating storage and regasification unit operated by Gastrade is becoming one of the main entry points for LNG into southeastern Europe and a strategic component of Athens’ ambition to establish Greece as an energy gateway between global LNG markets and Central and Eastern Europe.
LNG arriving by tanker can be converted back into gas at Greek terminals and fed into interconnected pipeline systems.
That means gas bought from producers thousands of kilometres away – particularly the United States – can potentially travel through Greece and Bulgaria towards Romania, Moldova and Ukraine, while expanded connections could increasingly serve North Macedonia, Serbia and markets further north.
The corridor can also handle gas originating in Azerbaijan and entering Europe through the Southern Gas Corridor.
That 3,500-km network connects the Shah Deniz gas field in the Caspian Sea with Europe through Georgia, Türkiye, Greece, Albania and the Adriatic Sea, with the Greece-Bulgaria interconnector providing another route towards southeastern Europe.
The result is a network in which Greece could increasingly function not merely as a consumer but as an entry and transit country for gas flowing north.
FROM RUSSIAN PIPELINE TO REVERSE ENERGY ROUTE
There is also a striking geopolitical reversal behind the project.
Part of the Vertical Corridor relies on the Trans-Balkan Pipeline, infrastructure that historically carried Russian gas southwards through Ukraine, Moldova and Romania towards Balkan markets.
Russia subsequently redirected much of its exports through TurkStream, leaving substantial Trans-Balkan capacity underused.
Europe is now attempting to use parts of essentially the same infrastructure in the opposite strategic direction: moving non-Russian gas northwards towards Moldova and Ukraine.
The change illustrates how dramatically Europe’s energy geography has shifted since Russia’s full-scale invasion of Ukraine in 2022.
Russian gas represented about 45% of EU gas imports in 2021. By 2025, its share had fallen to around 12%, according to European Commission figures.
At the same time, LNG’s share of EU gas imports increased from around 20% in 2021 to 45% in 2025 as Europe rapidly expanded LNG terminals, floating regasification units and cross-border connections.
The Vertical Corridor is part of that transformation.
U.S. GAS MOVES INTO THE PICTURE
Washington has strongly backed the corridor.
The U.S. Department of Energy hosted officials from Greece, Bulgaria, Romania, Moldova and Ukraine, together with European Commission representatives, in Washington in February to discuss development of the route.
Joshua Volz, a U.S. energy official involved in the initiative, said at the time that the corridor offered significant opportunities to expand U.S. LNG exports into Central and Eastern Europe.
Commercial agreements are beginning to reinforce that geopolitical objective.
U.S. LNG producer Venture Global and Greek joint venture Atlantic-SEE LNG Trade announced in June that they had doubled a long-term supply agreement under which at least 1 million metric tons of LNG annually is due to be purchased for 20 years from 2030.
The gas is intended to enter through Greece and potentially be distributed into Central and Eastern European markets through the Vertical Corridor. Venture Global has also secured around a quarter of the regasification capacity at Alexandroupolis.
That creates a commercial bridge between U.S. LNG production and southeastern European infrastructure.
For Washington, it represents both an export opportunity and a geopolitical instrument.
For Europe, it provides another source of gas.
But it also means European consumers become more exposed to global LNG competition and international price shocks.
Unlike traditional pipeline supplies tied primarily to regional infrastructure, LNG cargoes can be redirected towards whichever market offers the best price.
European Commission analysis says the continent’s greater dependence on LNG has therefore increased its exposure to developments in Asian gas markets, global shipping and geopolitical disruptions far beyond Europe.
NORTH MACEDONIA AT A STRATEGIC CROSSROADS
For North Macedonia, joining the initiative could be particularly significant.
The landlocked country has historically had limited gas-supply routes and remains connected to Bulgaria through the Kyustendil-Zidilovo interconnection.
Bulgaria’s transmission operator Bulgartransgaz says technical capacity for gas entering North Macedonia through that point is expected to rise from around 33.3 million kilowatt-hours per day to approximately 38.7 million kWh/day during 2027.
Participation in the Vertical Corridor potentially gives Skopje access to a wider pool of suppliers rather than merely another pipeline.
Gas could originate from LNG imported into Greece, including American cargoes, or from Azerbaijan through the Southern Gas Corridor.
For a small energy market, diversification can provide an important security advantage: the greater the number of suppliers and routes, the lower the vulnerability to disruption at a single source.
It could also strengthen North Macedonia’s physical integration with the EU energy market as the country pursues membership of the bloc.
But access alone does not guarantee lower prices.
The economics will depend on transmission tariffs, infrastructure capacity, LNG prices, long-term supply contracts and whether sufficient commercial demand emerges to keep the route competitive.
SERBIA’S MORE COMPLICATED BALANCING ACT
For Serbia, the geopolitical calculation is more complicated.
Belgrade has traditionally maintained close energy relations with Moscow and has remained heavily dependent on Russian gas.
Joining a corridor designed explicitly around diversification therefore gives Serbia an additional strategic option without necessarily requiring an immediate break with existing suppliers.
That distinction matters.
Energy diversification does not automatically mean replacing Russian gas entirely. Instead, new infrastructure gives governments and energy companies the ability to purchase gas from competing sources when commercial or political circumstances change.
For Serbia, access through North Macedonia and Greece could eventually place U.S. LNG and Azerbaijani gas alongside Russian supplies in a more competitive regional market.
It could therefore reduce Moscow’s leverage over one of Russia’s closest political partners in the Balkans even if Russian gas remains part of Serbia’s energy mix.
The development also fits a broader EU strategy of connecting Western Balkan energy systems more closely with the bloc.
BULGARIA – THE CRITICAL BRIDGE
Bulgaria sits at the heart of the emerging system.
Infrastructure projects are expanding the Greece-Bulgaria and Bulgaria-Romania transmission points, while Sofia is positioning its network as the physical bridge between Greek LNG terminals and markets farther north.
From Oct. 1, capacity from Greece into Bulgaria at the Kulata-Sidirokastro interconnection is scheduled to rise to about 93 million kWh per day, before increasing further to around 102.8 million kWh/day after the final project phase expected in early 2027.
The direction of travel is significant.
Infrastructure that once served a regional system dominated by Russian gas is increasingly being configured to allow supplies to move in several directions.
That gives southeastern Europe something it historically lacked: optionality.
UKRAINE CHANGES THE EQUATION
Ukraine is perhaps the most strategically important destination.
Its vast underground gas storage capacity can potentially receive supplies transported north through Greece, Bulgaria, Romania and Moldova.
Regulators and transmission operators have already introduced discounted capacity products aimed at making the Trans-Balkan route commercially competitive for gas moving towards Ukraine.
Moldova’s energy regulator said routes through Greece, Bulgaria, Romania and Moldova allow gas – including LNG originating in the United States – to reach Ukraine and its underground storage facilities.
The system could become increasingly important as Europe searches for alternative ways to guarantee Ukrainian energy supplies while Russian attacks continue to put pressure on the country’s infrastructure.
It also creates a remarkable reversal in European energy geography: Ukraine, once a principal transit route carrying Russian gas towards Europe, could increasingly become the northern destination of gas entering the continent through the Mediterranean.
HUNGARY AND SLOVAKIA
The corridor’s enlargement also has implications for Hungary and Slovakia, two Central European countries where the future of Russian gas supplies has remained particularly sensitive.
Operators FGSZ of Hungary and EUSTREAM of Slovakia are already involved in the initiative.
Adding Serbia and North Macedonia creates another potential branch connecting Balkan networks with Central European markets.
That does not mean U.S. or Azerbaijani gas will immediately displace Russian supplies.
Pipeline capacity, tariffs, contracts and market prices will ultimately determine how much gas actually flows.
But strategically, every additional interconnection reduces the importance of any single route.
THE COMMERCIAL TEST
Infrastructure alone will not guarantee success.
One of the biggest challenges facing the Vertical Corridor has been making the route commercially attractive.
Moving gas across several national transmission networks can accumulate tariffs at each border, potentially making supplies more expensive than competing routes.
Operators and regulators have consequently worked on bundled capacity products and tariff reductions.
European institutions have also pushed for harmonised gas-quality rules and the removal of regulatory barriers that prevent fuller use of the Trans-Balkan Pipeline.
The European Commission has said greater south-to-north use of existing infrastructure could improve competition and market liquidity without requiring construction of an entirely new pipeline system.
The next stage will therefore be less about diplomatic declarations and more about whether traders actually book capacity.
A NEW ENERGY MAP FOR THE BALKANS
The inclusion of Serbia and North Macedonia shows that the Vertical Corridor is evolving beyond its original geography.
The emerging network now brings together operators associated with Greece, Bulgaria, Romania, Moldova, Ukraine, Hungary, Slovakia, Serbia and North Macedonia.
It connects Greek LNG infrastructure with the Southern Gas Corridor, the Trans-Balkan Pipeline, Central European networks and Ukrainian storage.
On the western side, TAP already carries Azerbaijani gas through Greece and Albania to Italy, while the proposed Ionian-Adriatic Pipeline could one day extend that network through Montenegro and Bosnia and Herzegovina towards Croatia.
Croatia adds another strategic entry point through its Krk LNG terminal, potentially supplying Central Europe and, through future interconnections, Bosnia and other neighbouring markets.
Kosovo remains between these emerging systems without a gas network of its own, with North Macedonia representing its most obvious potential connection if Pristina eventually chooses to develop one.
Behind that collection of pipes and interconnectors lies a larger geopolitical contest.
Russia built much of its influence in Central and Eastern Europe partly through long-term energy relationships and pipeline dependence.
The United States has emerged as a major LNG supplier seeking a larger European market.
Azerbaijan has become another strategically important source for southeastern Europe.
Greece wants to turn its geography into an economic and geopolitical advantage by becoming a gateway for those supplies.
Bulgaria wants to become their principal northbound transit route.
Ukraine needs diversified energy access.
And Serbia and North Macedonia now have an opportunity to plug more deeply into that emerging system.
The transformation will not happen overnight.
Europe will continue consuming natural gas from multiple sources while simultaneously attempting to reduce overall fossil-fuel use under its climate policies. LNG prices will remain exposed to competition from Asia, infrastructure will require investment, and regional transmission tariffs will determine whether the new routes are commercially viable.
But the direction of Europe’s gas map has already changed.
For decades, southeastern Europe sat near the end of pipelines carrying energy from Russia.
The Vertical Corridor is based on a different proposition: gas arriving from the global market at Europe’s southern shores and moving north.
With Serbia and North Macedonia joining that network, the Western Balkans are increasingly becoming part of that reversal.