In view of the increasing tensions over the Russian troop build-up along Russia's border with Ukraine, NATO member Spain has deployed four fighter jets to Bulgaria.
Some 130 soldiers had already arrived at the air base Graf Ignatiewo in Bulgaria - another member of NATO - in recent days, the Spanish air force announced.
The Eurofighter aircraft are to strengthen air surveillance over the Black Sea and intercept Russian aircraft, La Vanguardia newspaper reported.
In April, the four fighter jets are to be transferred to the Baltic States.
The support of other NATO member states for Bulgaria is considered necessary because Bulgaria is still equipped with outdated Soviet-era MIG-29 fighter jets.
Bulgaria is to receive eight US F-16 fighter jets by the end of 2024.
