The Russian diplomat is the sixth to be expelled by NATO member Bulgaria since October 2019 for suspected espionage.
Russia’s embassy in Sofia said in a statement that the expulsion of its military attache was groundless and that Moscow reserved the right to respond.
“The unreasonable expulsion of the head of the representation of the Ministry of Defence of the Russian Federation does not contribute to the development of dialogue between our countries in the military sphere or to the strengthening of stability in the Black Sea region,” it said.
Bulgarian prosecutors said the Russian diplomat had been seeking sensitive military information, including on the number of U.S. troops deployed in Bulgaria during military drills.
Prosecutors said they had evidence that the diplomat had been in contact with a Bulgarian citizen with access to classified information to whom money had been offered.
After the announcement of the expulsion, the U.S. and British embassies in Sofia expressed support for Bulgaria’s efforts to protect its sovereignty and security.
Earlier this month, Russia’s foreign ministry spokeswoman said Moscow was concerned by growing NATO activity in the Black Sea. She said NATO military drill scenarios included possible attacks on Russian territory, while infrastructure was being upgraded and weapons deployed in Bulgaria and Romania.
Bulgarian Prime Minister Boyko Borissov has dismissed such concerns but has confirmed that Bulgaria is upgrading its airports to host eight new F-16 fighter jets it bought from the United States. It has also ordered two new patrol ships to replace ageing Soviet-era vessels to improve its compliance with NATO standards.
In the Communist times, Bulgaria was Moscow’s most reliable ally in eastern Europe. Despite periodic strains in post-communist ties, Russia remains Bulgaria’s biggest energy supplier and the two countries retain close cultural and other links.