President Vladimir Putin says Russia hasn't yet fulfilled a contract to send sophisticated S-300 air defense missile systems to Syria.
Russian officials have said that Moscow signed a contract for the delivery of the powerful missiles a few years ago, but have been coy about whether any of them have been delivered.
Speaking after a Russia-EU summit Tuesday, Putin defended the deal, saying it isn't against international law, but added that Russia hasn't yet fulfilled it.
The U.S. and Israel have strongly warned Russia against delivering the missiles, which would dramatically increase Syria's air defense capability.
Russia has been a key supporter of Syrian President Bashar Assad's regime, protecting it from United Nations sanctions and providing it with weapons despite the two-year civil war.