Russia has completed the delivery of S-300 air defense systems to Iran, the Federal Service for Military-Technical Cooperation said Thursday.

"Yes, it is through with the supplies," the FSMTC official said in reply to a question.

Iranian Defense Minster Hossein Dehghan late last August said Tehran hoped the supplies would be completed within a month.

The contract for selling S-300 to Iran was concluded back in 2007 only to be suspended in 2010. In the spring of 2015 Russian President Vladimir Putin lifted the ban from the sale of S-300 to Iran. The contract took effect in November 2015.

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.