Iran has deployed a Russian S-300 surface-to-air missile defense system at its underground Fordow nuclear facility, according to Reuters.
Iranian state media showed trucks arriving at the location with missile launchers being aimed toward the sky. Iran has not said if the S-300 system is fully operational.
"Our main priority is to protect Iran's nuclear facilities under any circumstances," Brigadier Gen. Farzad Esmaili, commander of the Islamic Revolutionary Guards Corps' (IRGC) Air Defense Force, told state TV.
Russia began delivering the system to Iran earlier this year under a contract signed in 2007. The delivery had been held up by international sanctions over Iran's nuclear program, but those sanctions have now been lifted.
Earlier this month, Iran said Russia delivered the main parts of the system to the country, adding that the missile would be completely delivered by 2016.
Critics say it's more proof that Iran plans to build nuclear weapons even though the regime denies it. Ayatollah Ali Khamenei said that the country's military power was for defensive purposes.
"The S-300 system is a defense system not an assault one, but the Americans did their utmost to prevent Iran from getting it," Khamenei said in a speech on state TV Sunday.