Opponents of the programme say the weapons are capable of carrying nuclear warheads, an argument categorically denied by Tehran's political and military authorities.
Tehran's ballistic missile tests in late 2015 brought new sanctions by the US against Iran on January 17.
The punitive measures were announced a day after international sanctions were lifted following the entry into force of a July 2015 nuclear agreement.
Tehran's ballistic missile tests in late 2015 brought new sanctions by the US against Iran on January 17.
The punitive measures were announced a day after international sanctions were lifted following the entry into force of a July 2015 nuclear agreement.