Editor’s Note: Please also see Five American Weapons of War ISIS Should Fear as well as Five Israeli Weapons of War ISIS Should Fear.

Over the past year, ISIS has scored a series of remarkable victories over Iraqi, Kurdish and Syrian forces. It has succeeded despite a lack of access to the heavy weaponry that its opponents regularly field. Indeed, the heavy weaponry that ISIS has acquired has come mostly from “battlefield appropriation,” picking up the leftover weapons of its defeated foes.

ISIS has won by exploiting the vulnerabilities of its enemies, which take the form of Western military organizations, while lacking their fighting and communications discipline. This allows ISIS to identify, in both tactical and operational terms, weak points that can cause an entire enemy position to cave in upon itself. In essence, ISIS has an operational form that allows decentralized commanders to use their experienced fighters against the weakest points of its foes. At the same time, the center retains enough operational control to conduct medium-to-long term planning on how to allocate forces, logistics, and reinforcements.

ISIS hasn’t been discriminating in its use of weapons; the group fights with whatever it can find. However, several systems have become common to ISIS fighting units. Typically, these are mobile, easy to use and easy to service. This article concentrates on five categories of weapons that have enabled ISIS’ path to prominence.

Technicals:

The rise of the technical gives lie to one of the enduring myths of maneuver warfare. In brief, this myth concentrates on the rise of the tank and the armored personnel carrier as innovations that restored maneuver to the battlefield after World War I. The myth leads to an over-emphasis on the characteristics of particular systems (tanks surely vary in quality, but generally not in war-winning ways), and a de-emphasis on the tactical and operational innovations, which make modern maneuver warfare possible.

In situations where the attackers can avoid assaulting the prepared defenses of enemy forces, in which they do not seek to create their own defensive hardpoints, and in which they don’t face a foe capable of concerted counter-offensive action, a Toyota pickup truck isn’t as good as a tank; it’s better.

The truck is easier to maintain, faster, and gets better fuel economy than the tank. It’s also expendable. Technicals have mounted heavy machine guns as well as artillery and light anti-aircraft weaponry, including AA missiles. This doesn’t mean that ISIS has completely eschewed the use of dedicated military vehicles. Rather, the group has found uses for them within its broader fighting ethos. For example, the initial penetration of an Iraqi military base recently seized by ISIS was reportedly by Humvees disguised as Iraqi Security Forces.

And ISIS has undoubtedly acquired some tanks. It reportedly operates several dozen T-55s, and well as about a dozen T-72, although airstrikes may have attrited that number somewhat. While ISIS has captured some M1A1 Abrams given to Iraqi forces from the United States, putting these vehicles into useful service will prove far more difficult, as requirements for spares and ammunition are more complicated.

Anti-tank weaponry:

The Syrian Army has used tanks extensively against both the Free Syrian Army and ISIS. Syrian regular forces have a long-term reputation for falling short in combined arms warfare, but just because a force is unskilled in offensive armored tactics doesn’t mean that it can’t put tanks to good use. Tanks are effective defensive weapons, especially against light infantry forces that lack heavy weapons. Such forces can surely kill tanks (“killing tanks is fun and easy,” as Marines are reputed to say) but armor nevertheless is a problem that they need to solve.

ISIS has reputedly used several different kinds of anti-tank weaponry, and has killed several varieties of tank. This includes Konkur and Komet anti-tank guided missiles (mainly seized from the Syrian Army), as well as the Chinese HJ-8 (taken in some cases from the Free Syrian Army), and Osa 90mm rockets. ISIS has also killed tanks through more traditional means, such as the use of RPGs, improvised explosive devices, and infantry placed charges. Targets include not only the old Soviet tanks (mainly T-55s and T-72s) operated by Syria, but also the much more modern M1A1 Abrams main battle tank.

Anti-aircraft weaponry:

Thus far, ISIS has used a variety of light anti-aircraft weaponry in both Iraq and Syria. This weaponry has served to deter both the Syrian and Iraqi air forces (the latter more than the former), in large part because of the modest capabilities of these forces. A recent report from Small Arms Survey added some detail on the anti-aircraft weaponry currently owned by ISIS. The weapons used include light anti-aircraft artillery (mostly stolen from the Iraqi and Syrian armies), shoulder-fired SAMs (including the Strela and Igla; reports of Stingers have not been confirmed), and heavy machine guns. ISIS has not, to our knowledge, attempted to put any of the aircraft it captured from Syria (including MiG-21s) into service, and the U.S. air campaign probably makes such an eventuality even less likely.

This level of ordnance can’t defeat a concerted air campaign pursued by a major, modern air force. Indeed, unless ISIS gets incredibly lucky, it’s unlikely that the US and its coalition partners will lose even a single aircraft (although A-10s should probably take some care). However, if the United States ever expects the Kurds or the Iraqis (not to mention the Free Syrian Army) to conduct offensive operations on their own, it’ll need to ensure that they’re supplied with adequate air support. The United States has, it’s fair to say, utterly failed at this project so far.

Artillery:

Light insurgent forces often fall short in terms of artillery, but ISIS has managed to acquire a respectable arsenal. ISIS reportedly fields a wide range of mobile artillery, some mounted in trucks. This includes traditional infantry operated mortars, as well as a variety of larger, towed pieces. In particular, ISIS has managed to seize a large number of M-46 130mm field guns. ISIS has also become adept at creating makeshift artillery by mounting missiles and rockets intended for different purposes (sometimes including ground attack) from its trucks and other vehicles.

This gives ISIS a punch that more conventional forces need to respect. It has also given ISIS the ability to conduct extended sieges of defended positions in the face of conventional and air attack, as demonstrated in its recent seizure of Tabqa airbase.

Assault Rifles:

The primary infantry weapon of ISIS has, unsurprisingly, become the AK-47 assault rifle and its variants. AK-47s are readily available in Syria and neighboring countries, and ISIS has sufficient cash to procure modern, reliable models, even as prices for guns and ammunition have increased. ISIS also has a well-regarded system of training, and focuses on experienced fighters. While the AK-47 is reputed to be the weapon of the ignorant and the untrained, the weapon becomes considerably more effective in the hands of experienced fighters with a grasp of modern infantry tactics. When supplemented with a variety of other light weapons, including RPGs, rockets, and light mortars, an AK-47 equipped ISIS team can fight formidably on both the offense and the defense. Focusing on the AK-47 also reduces ISIS’ logistical complications.

Conclusion:

The big victories won by ISIS earlier this year allowed the group to take control of a large amount of American weaponry, previously operated by America’s Iraqi and Kurdish allies. Apparently, some of the airstrikes launched by U.S. and coalition forces have concentrated on these weapons. However, apart from the few instances noted above of ISIS using tanks and Humvees, we have little sense of how the group will try to fit these weapons into its operational concept. We also don’t know how ISIS will react to the massive expansion of the Western air campaign over the past few weeks.

We should also not understate the flexibility of ISIS operations. ISIS has successfully conducted territorial defense against all of its enemies, indicating that it’s not simply a “grab and run” kind of group. There’s no doubt that the U.S. campaign creates huge problems for ISIS, but we can expect from its behavior thus far that it will respond through dangerously professional means.

Robert Farley is an assistant professor at the Patterson School of Diplomacy and International Commerce. His work includes military doctrine, national security, and maritime affairs. He blogs at Lawyers, Guns and Money and Information Dissemination and The Diplomat. Follow him on Twitter:@drfarls.