Russia transported a division of S-400 missile defense systems to Serbia as part of a military exercise in the Balkan state, the RIA news agency cited Russia’s Defense Ministry as saying on Thursday.

Russia has also sent a Pantsir missile system battery to Serbia, it said, adding it is the first time the systems would take part in a drill abroad.

The drill called “Slovenian Shield 2019” aims to coordinate joint efforts of the Serbia-Russia anti-aircraft defense units to prevent an air threat.

The transport of the S-400s, as well as the Pantsir missile system, were moved to Serbia by an Antonov An-124 Ruslan transport aircraft landing at the Batajnica military base outside Belgrade.