Russia’s cut in gas supplies to Bulgaria following the war in Ukraine pushed Sofia to seek alternative sources and routes. Bulgaria had limited liquefied natural gas (LNG) import infrastructure of its own, making Türkiye an important option for its energy security. The agreement signed in 2023 between Turkish Petroleum Pipeline Corporation (BOTAŞ) and Bulgargaz allowed for the transfer of up to 1.5 billion cubic meters of natural gas annually over 13 years. At the time, the logic was clear: Bulgaria would reduce its dependence on Russia while gaining access to global LNG markets through Türkiye.

However, the 13-year BOTAŞ-Bulgargaz agreement soon began to be described as a heavy financial burden for Bulgaria rather than a strategic supply security instrument. Three years later, the parties chose to suspend the contract for 15 months and renegotiate it rather than terminate it. The capacity guarantee was said to have become expensive for Bulgaria.

One of the most controversial aspects of the agreement was that Bulgaria was required to pay not only for the gas it used, but also for reserved capacity. In 2023, this structure was seen as a form of energy security insurance. In effect, Bulgaria was paying to ensure that Türkiye’s infrastructure would be available when it needed LNG in the future. It was later stated that a significant portion of the capacity regarded as a guarantee in 2023 was not used by Bulgargaz. There has been no official statement from BOTAŞ, however, that a significant portion of its capacity remained unused. The issue has also raised questions under energy law, particularly regarding the future of long-term contracts.

In 2025, Bulgarian Energy Minister Zhecho Stankov said terminating the agreement could cost more than 2 billion euros. Other statements put the total contractual obligation at approximately 4 billion Bulgarian lev, or around $2.3 billion. This left Bulgaria facing a difficult equation. While the obligations arising from the commercial contract remained, Bulgaria was also seeking to change its terms through political and legal means.

The BOTAŞ-Bulgartransgaz relationship represents a different dimension from this commercial agreement. In January 2024, the transmission system operators of the two countries signed an operational interconnection agreement for the Strandzha Malkoclar border connection. The agreement defined a technical capacity of approximately 117.7 million kWh per day from Türkiye to Bulgaria.

The connection was important for Bulgaria’s long-term objectives because it opened the way for LNG, Azerbaijani gas and other sources to reach Bulgaria and the wider region through Türkiye’s transmission system. The two agreements therefore should not be confused. The BOTAŞ-Bulgargaz agreement is a long-term commercial contract concerning access to LNG terminals and gas transportation through the BOTAŞ network. The BOTAŞ-Bulgartransgaz agreement, on the other hand, is an operational agreement governing the interconnection of the two countries’ gas transmission systems at the border. This distinction is important when assessing Türkiye’s role in Balkan energy security. Although Bulgaria is renegotiating its contract with BOTAŞ, the strategic importance of gas flows through Türkiye has not disappeared.

Conditions changed in 3 years

After three years of discussions, the critical development came on July 6, 2026. Following a meeting in Ankara between President Recep Tayyip Erdoğan and Bulgarian Prime Minister Rumen Radev, BOTAŞ and Bulgargaz signed a protocol to suspend the existing commercial agreement for 15 months. The most important aspect of the arrangement is that Bulgaria will not have to pay for unused capacity during this period. The Bulgarian side will pay only for the capacity it actually uses, under improved commercial terms.

This is not a termination. More accurately, the parties have temporarily frozen the existing commercial structure of the contract, creating room for renegotiation. This is important because the billions of euros in obligations Bulgaria could face in the event of unilateral termination have not disappeared. However, the 15-month suspension gives Sofia a temporary way out of paying for unused capacity.

So, what changed between 2023 and 2026?

In 2023, Bulgaria’s priority was simply to secure gas supplies. However, the energy market in 2026 is very different from the conditions in 2023. Even unused capacity that was not considered important three years ago now carries strategic value. This case is a clear example of the tension between energy security and commercial optimization in the European energy market.

As the Russia-Ukraine war continues, the security of Ukraine’s natural gas storage infrastructure, the largest in Europe, remains at risk. European storage levels are behind those recorded during the same period last year, while the continent’s dependence on LNG has increased. The serious disruption to LNG and oil flows through the Strait of Hormuz caused by the U.S.- Israel-Iran war adds another layer of risk. The European Central Bank has pointed to the Strait of Hormuz as a critical transit point affecting approximately one-fifth of global LNG supplies.

In such an environment, capacity providing access to LNG terminals in Türkiye and to Türkiye’s natural gas transmission system should not be viewed merely as a commercial service to be used every day. It should also be considered an energy security option that can be activated during a crisis. Therefore, if the BOTAŞ-Bulgargaz agreement were being signed for the first time today, in August 2026, the price of capacity should be determined not only by actual use, but also by the energy security and flexibility value it provides.

Bulgaria’s approach should be examined more closely. Sofia did not terminate the agreement. Instead, it chose to freeze its terms for 15 months and renegotiate them, while agreeing with BOTAŞ that it would not have to pay for unused capacity during this period. This suggests that Bulgaria does not want to withdraw from Türkiye. Rather, it appears to be trying to transform its existing capacity into a more flexible and lower-cost structure. Bulgaria’s growing supply options in recent years are also behind this strategy. Azerbaijani gas, LNG coming through Greece, regional interconnections, and access to LNG through Türkiye have increased Sofia’s bargaining power. The possibility of Iran developing an alternative northern corridor through Armenia and Georgia to the Black Sea and Europe could also be added to this picture.

The Iran-Armenia-Georgia-Bulgaria route is a corridor idea that has been discussed in the past, and current war conditions give it a new strategic meaning. If such a connection becomes concrete in the future, Bulgaria’s dependence on gas access through Türkiye could decline further. But for now, the key point is different: Bulgaria’s decision to freeze the BOTAŞ agreement is not a withdrawal from an energy source. It may instead be an attempt to renegotiate the contract’s risk and cost structure. For this reason, the future of the BOTAŞ agreement will be an important test not only for Türkiye-Bulgaria relations, but also for the price Europe is willing to pay for its energy security.

Is Bulgaria really giving up the capacity, or is it using the bargaining power created by changing geopolitical conditions to purchase the same capacity again at lower fixed costs and with greater flexibility? The next 15 months of negotiations will provide the answer.