Russia says it will continue military cooperation with Iran despite an outstanding payment for its S-300 missiles.
The contract to supply the powerful S-300 missiles to Iran was signed between the nations in 2007.
The S-300 surface-to-air system, known as the SA-20 in the West, can track targets and fire at aircraft from a distance of 75 miles.
In addition, the S-300 missiles also feature high jamming immunity and are capable of engaging up to 100 targets simultaneously.
Russia says it is not willing to become an unreliable partner for Iran by suspending the ongoing military-technical cooperation, so it has decided to maintain the ties according to its international obligations.