Iran is awaiting Russia’s response to Tehran’s proposal to drop its lawsuit against Moscow over its failure to honor a contract on the delivery of S - 300 air defense systems.“The ball is in Russia's court, but we are ready to continue cooperation on S-300," Iranian Ambassador to Moscow Mahmoud Reza Sajjadi said on Friday, a news agency reported. Iran filed a complaint with the International Court of Arbitration in Geneva against Russia’s state-run arms export company Rosoboronexport in 2011 after Moscow failed to comply with its commitments to deliver S-300 air defense systems to the Islamic Republic. On June 6, 2013, Sajjadi said that Tehran will withdraw its lawsuit if Russia honors its contract. He said if Iran sees that Russia has changed its position on the delivery of S-300 systems, the Islamic Republic will also “change its conduct.” The Iranian ambassador’s remarks came after Russian Technologies (Rostech) CEO Sergei Chemezov said on May 30 that Moscow seeks to reach a settlement with Tehran to withdraw its lawsuit against Rosoboronexport over the canceled deal as Russia’s chances “to win the case are very slim.” Chemezov said that the US had applied heavy pressure on Moscow to stop the agreement under the pretext that the deal was against the sanctions of the UN Security Council. The Russian official, added, however, that Washington later changed its rhetoric, saying the UN resolution did not specifically mention the S-300 system and claiming that Russia had acted on its own. Under a contract signed in 2007, Russia was required to provide Iran with at least five S-300 defense systems. Russia, however, 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. The Iranian Army has previously announced that it is manufacturing an indigenous missile defense system similar to the Russian S-300 and will unveil it in the next Iranian calendar year (beginning March 21, 2014).