Iranian state media says the military has begun deploying a Russia-supplied S-300 air defense system around the underground Fordo nuclear facility.

Video footage posted late Sunday on state TV’s website showed trucks arriving at the nuclear 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.

Russia began delivering the S-300 system to Iran earlier this year after sanctions were lifted under a landmark nuclear agreement with world powers.