Spain will support fellow NATO member Bulgaria in air surveillance, the Balkan country's Defense Ministry announced, as the Western alliance bolsters its eastern flank amid soaring tensions with Russia.

Spain will send 130 military personnel and four Eurofighter jets to Bulgaria, according to the ministry. The first jets for the mission, which is scheduled to last until March 31, are expected this week at the Graf Ignatievo air base in southern Bulgaria.

The Netherlands will also deploy F-35 fighter jets for air policing over the southeastern European Union country later this year. According to reports, there have been repeated Russian provocations over the Black Sea in recent years.

Bulgaria, a former Eastern bloc country, has been a member of NATO since the end of 2004, but is still equipped with Soviet-designed MIG-29 fighter jets.

Sofia will receive eight brand-new U.S. F-16 fighter jets by the end of 2024. However, the delivery of the first jets will be delayed by several months, Defense Minister Stefan Yanev said on Tuesday.