Iran’s ambassador to Russia says Tehran has rejected Moscow’s proposal to provide the Islamic Republic with a substitute for the S - 300 systems, which should have been delivered under a bilateral arms deal.Mohammad Reza Sajjadi told Russia’s RIA Novosti on Monday that the proposed substitute, the Tor anti-aircraft system, “would be unable to fulfill the S-300’s functions” within Iran’s national defense system. Under a contract signed in 2007, Russia was required to provide Iran with at least five S-300 missile systems. However, Moscow refused to deliver the systems to Iran under the pretext that they were covered by the fourth round of the UN Security Council resolutions against Iran. In September 2010, then Russian President Dmitry Medvedev signed a decree that banned the delivery of the S-300 systems to the Islamic Republic. Iran has filed a complaint against Russia’s state-run arms export company Rosoboronexport with the International Court of Arbitration in Geneva. On May 30, Russian Technologies (Rostech) CEO Sergei Chemezov said that Moscow sought to reach a settlement with Tehran to have Iran withdraw its lawsuit against Rosoboronexport over the deal on S-300 as Russia’s chances to win the case “are very slim.” Following its failure to meet its contract commitments with Iran, Russia proposed to replace the S-300 systems with the Tor systems. Tor is a mobile and integrated surface-to-air missile system designed for operation at medium, low and very low altitudes. It can also engage aircraft, cruise missiles, unmanned aerial vehicles and ballistic targets. Chemezov said the United States had applied heavy pressure on Russia to cancel the agreement with Iran under the pretext that the deal was against the UN sanctions. The Russian official, added, however, that Washington later changed its rhetoric and said the UN resolution did not specifically mention the S-300 system. He said that the US claimed that Russia had acted on its own.