The IS military, including groups incorporated into it in 2014, openly operates and controls territory in multiple cities in Libya and Nigeria.

[17] The Islamic State's military is based on light infantry mobile units using vehicles such as gun-equipped pick-up trucks (technicals), motorbikes and buses for fast advances.

[38] Middle East Forum's Aymenn Jawad Al-Tamimi said, "They are highly skilled in urban guerrilla warfare while the new Iraqi Army simply lacks tactical competence.

All these men spent time detained in Camp Bucca during the American occupation of Iraq[40][41] Abu Omar al-Shishani, who was a sergeant in the Georgian Army before leading an IS unit in Syria, also became a prominent commander.

[46] In contrast to these elite forces, most of IS' troops were local militias with few heavy weapons, usually deployed as territorial defense units.

The Islamic State stood in sharp contrast to some other jihadist organizations such as the Caucasus Emirate which generally attempted to minimize their own casualties, and became notorious for its willingness to sacrifice many of its fighters.

[47][48] One high-ranking IS commander known for this approach was Abu Omar al-Shishani, who successfully employed swarming tactics during the Siege of Menagh Air Base and Battle of Tabqa Airbase.

Regional expert Joanna Paraszczuk sarcastically remarked that al-Shishani's tactics were based on the belief that "everyone want[s] to be a Shahid" (martyr),[48] although not all Islamic State commanders showed such a readiness to sacrifice troops.

For example, some troops were essentially ordered to "just run towards the [enemy] and fight or whatever" during the 2015 Battle of Hasakah, even though they were targeted by massive aerial bombardments and their attacks had no apparent strategic value.

[47] Technicals play an important role for IS in a variety of combat purposes, ranging from quick-reaction forces, to tank equivalents, to self-defendable car bombs that can attack heavily defended targets.

By 2021, the group was estimated to field about 10,000 fighters in Syria and Iraq, although it still possessed a far greater network of supporters and sympathizers which could potentially enable it to rapidly swell its ranks in the future.

[65] An IS deserter alleged that foreign recruits were treated with less respect than Arabic-speaking Muslims by IS commanders and were placed in suicide units if they lacked otherwise useful skills.

[96] IS has been able to strengthen its military capability by capturing large quantities and varieties of weaponry during the Syrian Civil War and the post-withdrawal Iraqi insurgency.

Observers fear that they have "advanced surface-to-air missile systems" such as the Chinese-made FN-6, which are thought to have been provided to Syrian rebels by Qatar and/or Saudi Arabia, and purchased or captured by IS.

Witnesses reported that MiG-21 and MiG-23 jets were flying over al-Jarrah military airport, but the US Central Command said it was not aware of flights by IS-operated aircraft in Syria or elsewhere.

[109] It has become especially adept at the construction and use of truck and car bombs, most notably quite sophisticated models which were fitted with armour, machine guns,[49] and/or firing ports.

[112] Sometimes, IS even used armoured personnel carriers as chassis for car bombs, or fitted them with unguided rockets to clear the path to the intended target.

In a letter to UN Secretary-General Ban Ki-moon, Iraq's UN Ambassador Mohamed Ali Alhakim said that the materials had been kept at the university and "can be used in manufacturing weapons of mass destruction".

The International Atomic Energy Agency said that the seized materials were "low grade and would not present a significant safety, security or nuclear proliferation risk".

According to one scientist involved in the project, the main value of the mustard gas to IS was not its impact on actual combat, but its effect in psychological warfare.

[109] According to the US military, IS used the chemical weapons effectively on a tactical level, but never managed to employ them in a way that impacted the larger strategic situation.