Russia has delivered the first part of an advanced missile defense system to Iran, Iranian media reported on Monday, starting to equip Tehran with technology that was blocked before it signed a deal with world powers on its nuclear program.

The S-300 surface-to-air system was first deployed at the height of the Cold War in 1979.

In its updated form it is one of the most advanced systems of its kind and, according to British security think tank RUSI, can engage multiple aircraft and ballistic missiles around 150 km (90 miles) away. […]