Russia has reportedly begun the delivery of the S-300 air defense system to Iran as part of a long-running contract between Tehran and Moscow. Russian news agency TASS quoted Vladimir Kozhin, an aide to President Vladimir Putin, as saying on Thursday that “the contract is being implemented, [deliveries of S-300s] are starting”. The official did not disclose further details. Last month, Sergei Chemezov, the chief executive of the Russian state-owned defense conglomerate, Rostec, said the deal for the S-300 delivery was already signed. Russia committed to delivering the systems to Iran under an $800 million deal in 2007. Moscow, however, refused to supply the systems to Tehran in 2010 under the pretext that the agreement was covered by the fourth round of the United Nations Security Council sanctions against Iran over its nuclear program. In April, Putin lifted the ban on the delivery of S-300 to Iran following a framework agreement between Iran and major powers, which led to the conclusion of a comprehensive nuclear accord on July 14.