NATO said it "respects" Serbia's decision to hold joint air military exercises with Russia in which the Russian S-400 and Pantsir-S air-defense missile systems are being deployed.
Russia said the long-range S-400 and the short-range Pantsir-S systems are being used in the Slavic Shield-2019 exercise to test joint action by the Russian and Serbian militaries to fend off air attacks.
Russia’s Defense Ministry said the surface-to-air missile systems are stationed at the Batajnica base, outside the Serbian capital, Belgrade.
It is the first time that an S-400 battalion and a Pantsir-S battery have appeared in military drills outside Russia, the ministry said.
In a statement to RFE/RL, NATO's press office said the alliance and Serbia "are partners and we respect Serbia’s right to make sovereign decisions about exercises on its territory.”
“This is a matter for Serbia and Russia," the NATO statement said, adding that "Serbia is a NATO partner" and that the Balkan country has a “good and productive relationship” with the Western alliance.
The S-400 is to be returned to Russia after the six-day drills end on October 29.
Serbian President Aleksandar Vucic has said the Pantsir system was purchased by his government.
Serbia maintains strong political and economic relations with Russia despite a proclaimed goal of joining the EU. Belgrade has pledged to stay out of NATO and refused to join Western sanctions against Russia over Ukraine.
NATO 'Respects' Serbia's Joint Military Drills With Russia