The beginning of October 2025 marked the resumption of large-scale Russian attacks on Ukraine’s energy infrastructure. For the first time since the spring campaign of strikes, the country once again faced widespread power outages.
For example, the Chernihiv region has implemented a 6/3 electricity supply schedule, under which consumers receive electricity for six hours followed by a three-hour outage. At the same time, disruptions to electricity and water supply have been reported across the Kyiv, Sumy, and Odesa regions. In the city of Odessa alone, more than 46,000 electricity consumers were left without power.
The attacks are accompanied by sustained pressure on critical nodes of the power system, targeting both generation assets and electricity transmission and distribution infrastructure.
This signals the beginning of a new phase in the “energy” war against Ukraine. In contrast to previous years, the campaign against Ukrainian energy infrastructure is now being conducted with the lessons of past winters in mind and with a targeted selection of objectives.
Enemy Strategy: Strikes on Energy Infrastructure and Pressure on Nuclear Facilities
It is now evident that the aggressor has shifted its operational focus. While large thermal power plants were the primary targets of aerial attacks during 2022–2024, the current campaign increasingly targets nuclear power facilities and the critical substations that provide them with off-site power.
The deliberate strike on the Slavutych substation, which supplies off-site power to the Chornobyl Nuclear Power Plant, represented a clear act of nuclear coercion. Following the strike, the Chornobyl Nuclear Power Plant experienced a complete off-site power outage lasting more than three hours. The loss of off-site power affected the spent nuclear fuel storage facilities as well as the protective confinement structures over the destroyed Unit 4 reactor.
Unfortunately, these actions are not isolated acts of psychological intimidation but rather part of a systematic campaign. The aggressor is seeking to exploit the vulnerability of Ukraine’s nuclear infrastructure as an instrument of coercion, including in pursuit of its objective of restarting the temporarily occupied Zaporizhzhia Nuclear Power Plant.
The Situation at the Zaporizhzhia Nuclear Power Plant: Risks Remain
On 23 September, the Zaporizhzhia Nuclear Power Plant experienced a loss of off-site power. Fuel reserves for the emergency diesel generators were estimated to sustain essential safety systems for approximately ten days. At the same time, a complete loss of backup power systems would create a risk of overheating the nuclear fuel, as safe cooling requires a continuous supply of electrical power.
Nevertheless, the plant’s technical design provides a degree of resilience that allows critical scenarios to be avoided for a limited period. All reactor units at the Zaporizhzhia Nuclear Power Plant are currently in a cold shutdown state, and even under the worst-case scenario, a Fukushima-type nuclear accident is considered highly unlikely. For the reactor cores to reach hazardous temperatures (above 500°C), they would require at least two months of uninterrupted heat buildup, which is highly unlikely given the plant’s existing heat removal systems.
However, this does not mean that the situation is entirely safe. The plant’s off-site power supply has not yet been fully restored. In addition, according to the International Atomic Energy Agency (IAEA), a series of explosions was reported in the vicinity of the plant, further increasing nuclear safety risks. Most importantly, there is currently no reliable information on the actual condition of the plant’s safety systems.
Nuclear Power Plants Under Pressure: How Resilient Are They?
Due to the extensive loss of thermal generation capacity, nuclear power plants located in government-controlled territory now provide the backbone of Ukraine’s electricity generation.
During peak demand periods, a significant share of electricity supplied to Kyiv and central Ukraine is generated by the Rivne and Khmelnytskyi Nuclear Power Plants, creating new vulnerabilities for the power system. The substations and high-voltage transmission lines connecting these nuclear power plants to major load centers have become critical elements of the power system. It is these assets that the aggressor is seeking to disable through deliberate, targeted strikes.
The vulnerability of these assets remains one of the key challenges during the autumn–winter period. Even the capital, despite its robust air defence system, continues to depend on energy infrastructure located beyond the city limits, particularly thermal power plants, many of which lack adequate protection against aerial attacks.
Current Status: Is the Power System Ready for Winter?
Despite the growing threats, Ukraine’s power sector entered October with a relatively high level of preparedness for the winter season. Ukraine’s underground gas storage facilities currently hold 12.7 billion cubic metres (bcm) of natural gas, with inventories expected to reach the target level of 13.2 bcm by the end of the month. Coal stockpiles are estimated at approximately 2 million tonnes.
Overall, 2.3 GW of generating capacity has already been restored across Ukraine, a further 3.7 GW is scheduled to be commissioned, and 1.8 GW of distributed generation capacity has already been deployed.
Taken together, these measures demonstrate the growing flexibility and resilience of Ukraine’s power system, particularly in light of ongoing efforts to decentralize electricity generation and further integrate with the European electricity market.
Despite more than 65,000 recorded incidents of damage to Ukraine’s energy infrastructure since 2022 —including 3,500 in 2024 alone — the power system continues to operate. This demonstrates its exceptional capacity for adaptation and resilience despite direct losses estimated at approximately USD 20 billion.
The Priority: Grid Stability and Distribution Network Protection
Thus, it is already possible to identify the most critical infrastructure assets from the perspective of protection and resilience. Distribution networks and substations remain the most vulnerable components of the power system, as many still lack adequate physical or electronic protection. These assets are typically among the primary targets of large-scale drone and missile attacks.
Another significant risk is the overheating of local distribution networks under overload conditions. Under such circumstances, even minor damage can trigger cascading outages at the district or regional level.
Will Blackouts Return?
Recently, Ukrenergo issued an appeal to Ukrainians urging them not to operate multiple high‑power appliances simultaneously during peak load hours (from 5:00 p.m. to 10:00 p.m.). Such measures help reduce stress on the electricity network and minimize the risk of emergency outages. However, these recommendations are already well known to consumers and are generally not regarded as a cause for particular concern.
Experts currently outline three baseline scenarios for the 2025/2026 winter season:
- Optimistic scenario – air defence systems successfully intercept the majority of attacks, while any electricity outages remain localized and short in duration.
- Medium scenario – large-scale attacks result in a generation deficit, requiring the implementation of scheduled power outages lasting 4–8 hours per day.
- Pessimistic scenario – simultaneous attacks on power generation facilities and electricity distribution infrastructure, together with the suspension of electricity imports from the EU, result in a risk of a nationwide blackout.
However, it should be noted that the likelihood of a nationwide blackout this winter remains low. Ukraine’s power system has repeatedly demonstrated its resilience and ability to maintain operations despite sustained aerial attacks. Therefore, the most likely scenario is the implementation of controlled, scheduled power outages in selected regions. Based on assessments by the transmission system operator, a nationwide blackout is not considered a likely outcome.
However, this assessment does not apply to the vulnerable border regions of Sumy, Chernihiv, and Kharkiv regions, which are already experiencing persistent disruptions to electricity supply. Critical energy infrastructure facilities in central Ukraine also remain at risk, particularly those supplying electricity to major urban centres.
Author: Vadym Lytvynenko, Executive Director of NVP ENERGO-PLUS LLC.
