As Iran threatens to attack Israel over the assassination of a Hamas leader in the Iranian capital, its long-vaunted missile program offers one of the few ways for Tehran to strike back directly, but questions loom over just how much of a danger it poses.

The program was behind Iran's unprecedented drone-and-missile assault on Israel in April, when Iran became the first nation to launch such a barrage since Iraqi dictator Saddam Hussein lobbed Scud missiles at Israel in the 1991 Gulf War.