On 8 October Kirill Budanov spent about twenty hours in the Bulgarian capital. His meeting with Prime Minister Rumen Radev stayed confidential at Budanov’s request. The next day former Interior Minister Tsvetan Tsvetanov posted a photo of the two of them. The government had to admit it. On 14 October Radev told parliament exactly what they discussed.
The timing was not accidental. The visit came immediately after the 6 October drone attacks on merchant ships in Bulgaria’s exclusive economic zone. One vessel, the Togo-flagged Alfa Watan, sank with its crew unaccounted for. The second, the Palau-flagged Able, was damaged by fire but its crew was rescued. Zelensky publicly stated that Ukrainian and Bulgarian naval contacts had confirmed a combined Russian attack using maritime and aerial drones. Radev, for his part, had just denied any such contacts or conclusive proof. The arrival of Zelensky’s closest aide the following day undercut that posture and made the secrecy itself a political liability.
Reactors: Kiev wants hardware, Sofia wants a project
Ukraine again asked for the two VVER-1000 reactors built for the unfinished Belene plant and still sitting in storage. These units, manufactured by Russia’s Atomstroyexport and paid for at roughly €600 million, have been the subject of intermittent talks for years. Kiev sees them as a relatively fast and cheaper way to complete units 3 and 4 at the Khmelnytskyi nuclear power plant, helping to offset the generation shortfall caused by repeated Russian strikes on Ukraine’s energy infrastructure. Ukrainian lawmakers had already approved the principle of the purchase in 2025, though commercial and logistical details never closed.
Radev gave the same answer he once gave Zelensky: no direct sale. Instead he proposed building Belene together, with EU and US participation. The official reason is safety and security of nuclear operations on Bulgarian soil. The real reason is economic and political. Selling the hardware would write off years of sunk investment at the Belene site, kill any residual chance of turning the long-dead project into a working plant, and forfeit the possibility of exporting power through Romania. Keeping the reactors and pulling in Western money preserves leverage and the prospect of converting a liability into a regional asset.
According to Radev, Budanov took the joint-construction idea seriously and promised to raise it with the Americans during his subsequent talks in Miami with Steve Witkoff and Jared Kushner. This is consistent with Kiev’s broader approach: Ukraine is not only hunting spare nuclear hardware; it is prepared to explore schemes in which Bulgaria retains the site while Ukraine contributes technology, operational expertise, and political support for Western financing. Whether such a structure can overcome the project’s history of cost overruns, political reversals, and the awkward fact that the reactors are of Russian design remains an open question. But the conversation itself shows that both sides understand the reactors as bargaining chips rather than simple commodities.
Gas: Sofia positioning itself as the regional intermediary
The second topic was gas transit through Bulgarian territory. Radev confirmed that Bulgaria is ready to supply not only Ukraine but also Romania, Moldova, Serbia, Hungary and Slovakia. This is not ordinary transit. It is a claim on the role of middleman between Western or southern supplies — primarily LNG arriving via Greek terminals and the Vertical Gas Corridor — and the markets of South-East Europe.
After losing Russian gas in 2022, Bulgaria has steadily built the argument that its geography and existing infrastructure make it the convenient corridor. Capacity expansions on the Greece-Bulgaria interconnector, works on the northern sections of the Vertical Corridor, and coordination with Romanian and Moldovan operators are all part of this positioning. A closed-door meeting with the former head of Ukrainian military intelligence, now Zelensky’s chief of staff, shows that the corridor is being discussed directly with Kiev, not only through Brussels or regional technical working groups. In an environment where Black Sea shipping routes are under pressure and winter energy security remains precarious for several countries, control of transit capacity translates into political weight.
Drones in the exclusive economic zone and the limits of silence
The drone attacks of 6 October (and subsequent strikes closer to territorial waters days later) exposed the vulnerability of commercial shipping in NATO countries’ exclusive economic zones. These zones are not sovereign territory, so the incidents do not automatically trigger Article 5. Yet the pattern — ships carrying grain or other cargoes hit by aerial and maritime drones, with crews killed or missing — raises the cost of remaining ambiguous. Zelensky’s public attribution to Russia and Radev’s initial denial of contacts created a contradiction that Budanov’s visit made impossible to ignore.
In parliament Radev said he raised the drone issue himself but that it was not the focus of the conversation. On paper that holds. In reality, a secret visit by the head of Zelensky’s office at the exact moment Sofia was trying to stay silent and avoid naming a culprit looks awkward. The optics were worsened by the fact that Budanov flew straight from Sofia to Miami for talks that also touched on shipping security. Quiet diplomacy becomes harder when drones are already operating inside a NATO country’s economic zone and ships are sinking.
Political cost for Radev
A prime minister who built his brand on scepticism toward military aid to Ukraine and talk of “peace through dialogue” walked into a trap. Secrecy let him talk without public commitments. The leak turned the conversation into a vulnerability. Kostadin Kostadinov’s Revival party attacks him for hypocrisy. The pro-European camp attacks him for opacity. The Foreign and Defence ministries publicly stated they had not been told about the visit. Even within Radev’s own pragmatic framing — extracting value from geography while avoiding deep military entanglement — the episode demonstrates the difficulty of conducting parallel tracks when events on the Black Sea force the issue into the open.
Radev’s government has already scaled back direct military support relative to previous cabinets, declined participation in certain coalitions of the willing, and emphasised diplomatic channels. At the same time it cannot ignore the energy and infrastructure opportunities that cooperation with Ukraine and Western partners can unlock. The result is constant balancing between a domestic electorate wary of entanglement and the practical need to convert Bulgaria’s location into concrete leverage.
Bottom line
Bulgaria is not picking a moral side. It is negotiating. The reactors stay in Sofia — that is the red line. Gas transit is offered on terms that strengthen Bulgaria’s regional weight. Kiev gets a channel and a chance to float the Belene idea in Washington. The West gets another potential lever on a project frozen for years and an additional route for non-Russian gas into South-East Europe.
The secrecy and the leak show the limits of this approach. When drones already operate inside a NATO country’s exclusive economic zone and commercial ships are being sunk, quiet talks do not stay quiet for long and begin to work against the person who held them. Radev is trying to turn both the reactors and the pipelines into assets rather than liabilities. Whether that works depends on real Western money for Belene, on how far Kiev is prepared to go beyond a simple purchase, and on whether the Black Sea can be stabilised enough for commercial shipping to function without constant escalation. In the meantime, the bargaining continues — more openly than either side preferred.
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