Video footage posted late Sunday on state TV’s website showed trucks arriving at the site and missile launchers being aimed skyward. It did not say whether the system was fully operational.
The large, underground facility is located in some 100 kilometers (60 miles) south of the capital, Tehran.
Iran deploys S-300 system in Fordo
Russia began delivering the S-300 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, which were lifted this year under an agreement with world powers.
“S-300 air defense system is a defensive instrument, not offensive,” Iran’s Supreme Leader Ayatollah Ali Khamenei said earlier on Sunday. “But the Americans applied all their efforts for Iran not to have it.”
The Fordo site, built at a depth of 90 meters (300 feet) below a mountain, was revealed by Western nations in 2009.