Military activity of ISIL

Command structure

According to the Institute for the Study of War, ISIL's 2013 annual report reveals a metrics-driven military command, which is "a strong indication of a unified, coherent leadership structure that commands from the top down". 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."

ISIL's Military Council is made up of numerous former military officers from the Saddam Hussein era. Commanders have included Haji Bakr, a colonel; Abu Abdulrahman al-Bilawi, a captain; and Abu Ayman al-Iraqi, a lieutenant colonel, who all graduated from the same Iraqi military academy. Abu Muslim al-Turkmani, al-Baghdadi's former deputy, was a Directorate of General Military Intelligence lieutenant colonel. All these men spent time detained in Camp Bucca during the American occupation of Iraq Abu Omar al-Shishani, who served in the Georgian Army before leading an ISIL unit in Syria, also became a prominent commander.

ISIL’s fighters are reportedly organised into seven branches: infantry, snipers, air defence, special forces, artillery forces, the “army of adversity”, and the Caliphate Army. This force structure is largely replicated in each of its designated provinces, with the most skilled fighters and military strategists in each area serving in the special forces unit, which is not allowed to redeploy to other provinces. Parallel to this structure is the Caliphate Army, which is directed by ISIL’s central command rather than its provincial leadership. Made up overwhelmingly of foreign fighters, it is deployed to assist in battles across the Islamic State. There is also an all-female Al-Khansaa Brigade tasked with policing religious laws. According to battle reports, ISIL often operates in small mobile fighting units.

The group also operates outside areas it largely controls using a clandestine cell system. An ISIL-linked senior militant commander in Sinai told Reuters; “They [ISIL] teach us how to carry out operations. We communicate through the internet, ... they teach us how to create secret cells, consisting of five people. Only one person has contact with other cells. They are teaching us how to attack security forces, the element of surprise. They told us to plant bombs then wait 12 hours so that the man planting the device has enough time to escape from the town he is in.”

Troops in Iraq and Syria

In June 2014, ISIL had at least 4,000 fighters in Iraq, and the CIA estimated in September 2014 that it had 20,000–31,500 fighters in Iraq and Syria. The Syrian Observatory for Human Rights estimates that the force numbers around 80,000–100,000 total (up to 50,000 in Syria and 30,000 in Iraq). Reuters quoted "jihadist ideologues" as claiming that ISIL has 40,000 fighters and 60,000 supporters, while a Kurdish leader estimated in November 2014 that ISIL's military had 200,000 fighters.

Some Syrian rebel factions have defected to ISIL, including the 1,000-strong Dawud Brigade in July 2014. In addition to jihadists and other volunteers, ISIL is known for forcing other rebel groups to fight for it, as well as conscripting individuals. Many reports say troops and equipment move between various parts of Iraq, Syria, and Lebanon as tactical needs arise.

Foreign fighters in Iraq and Syria

There are many foreign fighters in ISIL's ranks. In June 2014, The Economist reported that "ISIS may have up to 6,000 fighters in Iraq and 3,000–5,000 in Syria, including perhaps 3,000 foreigners; nearly a thousand are reported to hail from Chechnya and perhaps 500 or so more from France, Britain and elsewhere in Europe." Chechen leader Abu Omar al-Shishani, for example, was made commander of the northern sector of ISIL in Syria in 2013. According to The New York Times, in September 2014 there were more than 2,000 Europeans and 100 Americans among ISIL's foreign fighters. As of mid-September 2014, around 1,000 Turks had joined ISIL, and as of October 2014, 2,400–3,000 Tunisians had joined the group. An ISIL deserter alleged that foreign recruits were treated with less respect than Arabic-speaking Muslims by ISIL commanders and were placed in suicide units if they lacked otherwise useful skills. According to a UN report, an estimated 15,000 fighters from nearly 70 countries have travelled to Iraq and Syria to join militant groups, including ISIL.

Despite thousands of foreign volunteers, Reuters has stated that according to jihadist ideologues 90 percent of ISIL's fighters in Iraq are Iraqi and 70 percent of its fighters in Syria are Syrian.

Nationalities fighting for ISIL

This list does not include citizens of Syria, or Iraqi Arabs.

As of September 29, 2015, the CIA estimated that 30,000 foreign fighters had come to the Islamic State. As of October 2015, 21% came from Europe, 50% from Western Asia or North Africa, and 29% from elsewhere; according to the Global Terrorism Index and other sources, they were of the following nationalities:

Allegiance to ISIL from groups outside Iraq and Syria

Conventional weapons

The most common weapons used against US and other Coalition forces during the Iraq insurgency were those taken from Saddam Hussein's weapon stockpiles around the country. These included AKM variant assault rifles, PK machine guns and RPG-7s. ISIL has been able to strengthen its military capability by capturing large quantities and varieties of weaponry during the Syrian Civil War and Post-US Iraqi insurgency. These weapons seizures have improved the group's capacity to carry out successful subsequent operations and obtain more equipment. Weaponry that ISIL has reportedly captured and employed include SA-7 and Stinger surface-to-air missiles, M79 Osa, HJ-8 and AT-4 Spigot anti-tank weapons, Type 59 field guns and M198 howitzers, Humvees, T-54/55, T-72, and M1 Abrams main battle tanks, M1117 armoured cars, truck-mounted DShK guns, ZU-23-2 anti-aircraft guns, BM-21 Grad multiple rocket launchers, and at least one Scud missile.

ISIL shot down an Iraqi helicopter in October 2014, and claims to have shot down "several other" helicopters in 2014. 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 ISIL.

Aircraft

ISIL also captured fighter aircraft in Syria. The Syrian Observatory for Human Rights reported in October 2014 that former Iraqi pilots were training ISIL militants to fly captured Syrian jets. 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 ISIL-operated aircraft in Syria or elsewhere. On 21 October, the Syrian Air Force claimed that it had shot down two of these aircraft over al-Jarrah air base while they were landing.

Non-conventional

ISIL captured nuclear materials from Mosul University in July 2014. 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". Nuclear experts regarded the threat as insignificant. 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".

Reports suggest that ISIL captured Saddam era chemical weapons from an Iraqi military base and has deployed chlorine gas based chemical weapons against Iraqi Government forces, Syrian Government and Syrian Opposition Forces, and unidentified chemical weapons against Kurds in Kobanî, Syria.

ISIL has a long history of using truck and car bombs, suicide bombers, and IEDs.