The agreement was signed by Iranian Defense Minister Brigadier General Hossein Dehqan and his visiting Russian counterpart General Sergei Shoigu in a meeting in Tehran on Tuesday, Farsnews reported .
The Iranian and Russian defense ministers agreed to resolve the existing problems which have prevented the delivery of Russia's advanced air defense systems to Iran in recent years .
The two sides also agreed to broaden their defense cooperation and joint campaign against terrorism and extremism .
In 2007, Iran signed a contract worth $800mln to buy five Russian S300 missile defense systems .
But the deal was scrapped in 2010 by the then-Russian President Dmitry Medvedev, who was unilaterally expanding on sanctions against Iran imposed by the UN Security Council .
Iran filed a $4bln lawsuit against Russia in the international arbitration court in Geneva, which is currently pending review .
Moscow has struggled to have the lawsuit dropped, including by offering the Tor anti-aircraft systems as replacement, media reported in August, adding that the offer was rejected by Tehran .
The Antei-2500, however, may be a better solution, the reports said. The system does not formally fall under the existing sanctions against Iran while still being useful for the Middle-Eastern country .
While the S-300 was developed for the use by missile defense forces, the Antei-2500 was specifically tailored for the needs of ground forces, which could also be an advantage for Iran, known for its large land force .
Later, Iran rejected the offer, stressing that it would not change its order .
The S-300 is a series of Russian long range surface-to-air missile systems produced by NPO Almaz, all based on the initial S-300P version. The S-300 system was developed to defend against aircraft and cruise missiles for the Soviet Air Defense Forces. Subsequent variations were developed to intercept ballistic missiles .
The S-300 system was first deployed by the Soviet Union in 1979, designed for the air defense of large industrial and administrative facilities, military bases, and control of airspace against enemy strike aircraft .
