A spectator watches Sukhoi Su-30SM jet fighters of the Sokoly Rossii (Falcons of Russia) aerobatic team perform during the MAKS International Aviation and Space Salon in Zhukovsky, outside Moscow, Russia, August 29, 2015. REUTERS/Maxim Shemetov

MOSCOW (Reuters) - Russia will send the first S-300 air defense missile system to Iran on Thursday, Russia’s RIA state news agency reported on Wednesday quoting an unidentified source.

The missile system will be delivered under the terms of an earlier contract.