Iran has displayed parts of its new Russian-made air defence system during its Army Day celebrations.
Pictures released by the semi-official ISNA news agency showed S-300 missile tubes and radar equipment during a military parade in southern Tehran.
Iran insists the system is necessary to defend itself, but the US and Israel have criticised the sale.
The controversial contract got the go-ahead after last year’s deal to lift international sanctions on Iran.
Six world powers led by the US agreed in July to lift the sanctions which had locked down much of Iran’s economy for years, in exchange for limits on Tehran’s nuclear programme.