Just when you thought you’d seen it all in the six-year-long Syrian civil war, the conflict took another turn when Iran launched a missile attack against Islamic State militants in the province of Deir ez-Zour last Sunday. Iran depicted the attack, which was reportedly the first time Iran used missiles since the Iran-Iraq War, as a response to the ISIS attacks on the Iranian parliament and mausoleum of Ayatollah Ruhollah Khomeini earlier this month.

Although ISIS provided the immediate impetus for the attacks, there’s little doubt that Tehran wanted to send a secondary message to the United States and its allies, especially given that U.S. forces have begun attacking Bashar al-Assad’s forces in Syria. Indeed, Ramazan Sharif, a general in the Islamic Revolutionary Guards Corps (IRGC), told state-run media after the attacks: “The Saudis and Americans are especially receivers of this message. Obviously and clearly, some reactionary countries of the region, especially Saudi Arabia, had announced that they are trying to bring insecurity into Iran.”

Deterring regional adversaries from threatening Iran is the primary reason Tehran has amassed the largest ballistic missile forces in the Middle East. The missile program actually began under the Shah, but it was accelerated during the Iran-Iraq War in order to threaten Saddam Hussein with strikes deep in Iraqi territory. Since then, Iran has worked with countries like Libya, North Korea and China in order to develop a large and diverse arsenal of ballistic and cruise missiles that form one part of its three-leg deterrent strategy. With Iran now using missiles in conflict, it’s worth taking a closer look at the weapons in its arsenal.

Shahab-Series

The backbone of Iran's missile forces are the Shahab-series of liquid-fueled (mostly) short-range ballistic missiles (SRBM). There are three variants of the missile: The Shahab-1, Shahab-2 and Shahab-3. The Shahab-1 was the first missile Iran acquired and is based on the Soviet Scud-B missile. Iran reportedly purchased these initially from Libya and possibly Syria, but North Korea has been its main supplier. The Shab-1 has a reported range between 285–330 kilometers, and can carry a warhead of around one thousand kilograms. Iran is believed to have three hundred Shahab-1 rockets.

Later Iran acquired Shahab-2 missiles, likely from North Korea. This missile is based on the Scud-C and has a range of five hundred kilometers with a payload capacity of 770 kilograms. Iran first began testing the Shahab-2 in 1998, and it has been operational since at least 2004. Like the Shahab-1, the Shahab-2 is road-mobile, however, the Congressional Research Service has noted that: “Wartime experiences, such as in Iraq, show these missiles tend to operate within a radius of about 100 kilometers or less from their bases because of the need to ensure operational security and to be able to maintain key logistics support.” Tehran only purchased between 100–170 Shahab-2s from North Korea, but can now produce them indigenously (although it relies on some imported parts).

Most importantly is the Shahab-3, also a liquid-fueled, road-mobile missile. The Shahab-3 is the first medium-range ballistic missile Iran acquired, with a likely range of between 1,000-1,300 kilometers depending on the size of the payload. The payloads themselves are said to weigh between between 760 and 1,200 kilograms. The Shahab-3 is widely believed to be based on North Korea's No Dong-1 missile, which itself likely relied heavily on Soviet technology. Unlike the other Shahab-variants, the Shahab-3 is a two-stage missile with an engine and separate reentry vehicle. Iran's version of the missile was first flight tested in 1998. That test was unsuccessful, and a number of subsequent tests also failed. Consequently, the Shahab-3 did not enter into service until 2003.

It is unknown how many Shahab-3 missiles Iran has deployed, in part because Tehran appears to rely mostly on a number of variants of the missile, which go by a number of different names like the Emad and Ghadr. These later editions of the missile incorporate Pakistani technology, have a redesigned reentry vehicle, and improved navigation and guidance systems. It's possible, but unlikely, that some of these variants use solid fuel. They do have an improved range of somewhere between 1,500–1,800 kilometers, and perhaps as high as 2,500 kilometers.

Fateh-Series

The Fateh-series missiles are the solid-fueled counterparts of Shahab missiles. Like the Shahab-1 and Shahab-2, the Fateh-110 and Faeth-331 are short-range and road-mobile. The Fateh-110 is a single-stage missile with a range of 210 kilometers. It is likely more accurate than some of the earlier Shahab variants, with some estimates suggesting a circular error probable (CEP) of one hundred meters. Iran began developing the Fateh-110 in 1995, with the first test coming in May 2001. The missile became operational in 2004. The Fateh-313 extends the range of the Fateh-110 to roughly five hundred kilometers, and also has other upgrades such as greater accuracy. It is believed to have entered into service in 2015. The U.S. Treasury has accused Chinese companies of aiding Iran's development of the Fateh series.

Last year, Iran unveiled a new part of the Fateh family, called the Zolfaghar. When Iran first revealed the missile, Defense Minister Hossein Dehghan claimed it had a range of seven hundred kilometers. According to IHS Jane’s, “The Zolfaghar appears to be the same shape and size as earlier Fateh-110s, but the guidance system has been redesigned, seemingly so it sits closer to the nose. This may have freed up space for a larger solid-fuel motor, but has come at the expense of payload size, which clearly has been reduced.” Fars News Agency, which is close to the IRGC, reported that the Zolfaghar “is capable of carrying Multiple Reentry Vehicle (MRV) payloads,” although this seems unlikely. Iran claims that it used Zolfaghar missiles to attack Syria last Sunday, but Israeli intelligence believes that was actually a Shahab-3.

Sejjil

The Sejjil medium-range ballistic missile is the solid-fueled counterpart to the Shahab-3 liquid-fueled missile discussed above. According to CSIS's Missile Defense Project, the Sejjil missile has a similar size, weight and range to the Shahab-3. Specifically, the two-stage missile has a range of two thousand kilometers and can carry a warhead of between 500–1500 kilograms. Development reportedly began in the late 1990s, but the first test wasn't conducted until 2008. During a 2009 flight test, the missile flew around 1,900 kilometers. Although the Sejjil missile uses an Iranian design, it likely benefitted from Chinese assistance, with some commentators comparing it to the DF-11 and DF-15. Iran has claimed that it has developed multiple variants of the missile, including a Sejjil-3 missile that some analysts believe will have a maximum range of four thousand kilometers.

Khalij Fars

Last but not least, Iran has developed an anti-ship ballistic missile to enhance its anti-access/area denial strategy against the U.S. military in the Persian Gulf. Appropriately enough, Iran named this missile Khalij Fars (Persian Gulf). Based off of the Fateh-110, the Khalij Fars was first tested in early 2011, and coincided with Iran announcing the completion of a long-range, passive radar covering a 1,100 kilometer-radius. Later that year Iran announced that the missile had entered mass production. In tests since that time Iran has claimed, rather implausibly, the missile registered a 100 percent success rate in hitting ship-like platforms positioned in the Persian Gulf. According to Iranian media outlets, “the supersonic projectile, which carries a 650-kilogram warhead, is immune to interception and features high-precision systems.” An Iranian general has bragged in 2013, "Today, Iran has missiles that can crush U.S. warships like a can and send them deep into water.” Iran has also unveiled two variants of the Khalij Fars: the passive radar-guided Hormuz-1 and the active radar-guided Hormuz-2.

Conclusion

This is hardly a comprehensive list of Iran’s missile arsenal, which also includes a number of cruise missiles. Still, it provides readers with a basic overview of one of the most lethal capabilities of the IRGC. Ballistic missiles are also the most blunt prong of Iran’s deterrent strategy, which also includes the use of proxies and asymmetric naval warfare. Still, it is certainly something that U.S. Central Command has to plan for, especially as Iran and the United States come closer to fighting directly in the Syrian Civil War.

Zachary Keck is the former managing editor of The National Interest. You can find him on Twitter: @ZacharyKeck.

Image: A ballistic missile is launched and tested in an undisclosed location, Iran, March 9, 2016. REUTERS/Mahmood Hosseini/TIMA