Iran is believed to be increasing production of it's Shahab 3 IRBM (Intermediate Range Ballistic Missile.) This missile is basically 1960s technology, with the addition of GPS guidance. Russian and North Korean missile technology has been obtained to make the Shahab 3 work. This has resulted in a missile that apparently will function properly about 80 percent of the time, and deliver a warhead of about one ton, to a range of some 1,700 kilometers, to within a hundred meters of where it was aimed. By world standards, this is a pretty effective weapon.
Iran is believed to have been building Shahab 3s since 2004, even though they continue to refine the design, and conduct test firings. Iran is believed to have 50-100 Shahab 3s, and is building about one a month. But there are rumors that production is being increased, to as many as 7-8 a month. Israel appears to be the main target. Iran has threatened Israel with destruction, rather openly of late. Shahab 3's could be fired with high explosive warheads, and hit, with enough accuracy, to kill mostly Jews, and not Israeli Arabs or Palestinians.
Israel has threatened to retaliate with nukes if Israel is hit with chemical or nuclear warheads. Israel has Arrow anti-missile systems that can stop Shahab 3s, but only a few at a time. If Iran launched a dozen or more Shahab 3s simultaneously, some would get through. If Iran had several hundred Shahab 3s, they could launch most of them at Israel, using high explosive warheads, and do a lot of damage. Israel could respond with its own Jericho II missile, but this system was designed for use with nuclear weapons, and Israel apparently only has 20-30 of them. Israel could respond with air strikes, and cruise missiles from submarines in the Persian Gulf or Indian Ocean. But, again, this would appear as a limited response to massive Iranian missile attacks. An Iranian attack with nuclear warheads would kill a large number of Moslems, and even radical Iran might be put off by that, because Israel would likely respond in kind.
A large number of IRBMs could also be used to intimidate nearby Arab countries, as these missiles could damage oil production facilities.