Russia is upgrading its S-300 anti-missile defense systems which was supposed to be delivered to Iran.
"Since the original contract was signed a long time ago. He wouldn't offer specifics or say when the delivery would take place," Vladimir Kozhin, a presidential adviser on military matters was quoted as saying by RIA news agency on July 30.
In 2010, Russia had cancelled a contract to deliver the advanced missile system to Iran as it was pressurized from the West. But Putin lifted that self-imposed ban in April following an interim nuclear deal between Iran and world powers.
Moscow is seeking to reap economic and trade benefits now that a more comprehensive nuclear deal between Iran and world powers has been reached, which allows an easing of sanctions on the Islamic republic.
Israeli Prime Minister Benjamin Netanyahu said that Israel is in dismay at Russia's decision to supply the S-300s to Iran, and even the US has expressed concern.