Bulgaria has formally asked NATO to deploy additional fighter aircraft and counter-drone systems to the country following a series of attacks on commercial vessels in the Black Sea.
Defense Minister Dimitar Stoyanov announced the request.
He said Sofia had submitted a formal request to NATO's secretary general and the alliance's Supreme Allied Commander Europe and was awaiting a response.
The request followed several attacks on commercial shipping in the Black Sea, including strikes on two vessels off the Romanian coast and the loss of another vessel off Bulgaria.
Bulgarian authorities had previously said they considered Russian involvement in some of the incidents likely, but no conclusive public evidence has established Russian responsibility for the entire series of attacks.
Bulgaria also plans to discuss a joint counter-drone strategy with Romania and Turkey.