Editor's note: This series examines 10 categories of arms used in the Syrian conflict, a ghastly proving ground for much of what 21st-century militaries and militant groups can bring to war.

First known use: In May 2011, Qassem Suleimani, the commander of Iran's Quds Force, was said to be directly helping the Assad regime, according to the U.S. Treasury Department.

Other exterior groups include Hezbollah, which confirmed its involvement in Syria in April 2012.

Russia has sent its own combat troops and advisors, officially beginning in 2015:

The Kremlin's troop deployment began in September 2015 as “naval infantry”; it expanded as the needs of Assad’s troops grew. Under the cover of Russian warplanes, Syria troops gained the upper hand against rebel groups in several areas.

In late March 2016, Spetnaz participation at Palmyra was confirmed.

And Turkey:

On February 21, 2015, Ankara sent tanks, drones and surveillance planes, along with hundreds of troops into northern Syria allegedly to evacuate soldiers at an ancient Ottoman tomb in the Esmisi region of Syria.

In November 2015, Ankara sent 150 troops to Iraq's "Bashiqa military base near Mosul to protect Turkish forces training the Hashid Watani Sunni militia to fight Islamic State," Reuters reported shortly afterward. The deployment caused a row in Baghdad, as the additional Turkish troops arrived without any consultation from Iraqi Prime Minister Haider al-Abadi.

Turkey's special forces have also been known to cross the border into northern Syria as recently as May.

The U.S.-led coalition has dispatched hundreds of trainers and advisors to help various groups battle ISIS in Iraq and Syria. Here's how many advisors have been sent to both countries as of July 11, 2016:

U.S., 4,647

U.K., 1,350 (including the 250-troop increase ordered in late June)

Australia, 460

Italy, 440

Spain, 340

France, 240

Germany, 120

Hungary, 120

Netherlands, 130

Denmark, 130

New Zealand, 110 (143 authorized on June 20)

Norway, 80

Canada, 70

Finland, 50

Poland, 50

Sweden, 30

Portugal, 30

Belgium, 20

Latvia, 10



Data via DOD, Institute for the Study of War, Omran Center for Strategic Studies.

U.S. troops against ISIS

The U.S. fight against the Islamic State in Syria is inextricably linked to the fight in Iraq. Here's a brief history of U.S. troops in the Iraq battlespace during the course of the Syrian war:

In June 2014, an initial contingent of 170 U.S. soldiers was sent to Baghdad as advisors.

The total jumped to 1,550 six months later at the start of 2015.

It nearly doubled four months later, topping 3,000 in April 2015.

An announcement on April 18, 2016,announcement brought the total to 4,087, not including “another estimated 1,000 U.S. troops who are in the country but are not part of the Pentagon’s official count, including special operations forces, some logisticians, troops on temporary duty and forces who are rotating in to replace departing forces,” according to Stars and Stripes.

An additional 560 U.S. troops are headed to Iraq, Defense Secretary Ash Carter announced on July 11, raising the American troop cap to 4,647.

Four-hundred more deployed to Iraq in early September 2016, bringing the total to 4,460 versus a cap of 4,640.

Forward-deployed Western troops: The first news of coalition members battling ISIS came when Canadian special forces fought off sniper and small arms attacks in northern Iraq in January 2015.

This was after U.S. special forces raids—one in search of Jim Foley allegedly on July 3, 2014, outside of Raqqa—just after Abu Bakr al-Baghdadi gave his speech from Mosul declaring himself “caliph.”

President Obama authorized a contingent of 50 special operations troops into Syria on October 2015, nearly 16 months after the first contingent of American troops arrived in Iraq to fight ISIS. That group grew by 250 to an authorized cap of 300 in late April.

In late 2015, U.S. Defense Secretary Ash Carter announced the creation of the Pentagon’s “expeditionary targeting force” of special operators with kill/capture missions.

Early precedent: May 16, 2015—Abu Sayyef (raid also involved British SOF).

Recent publicly announced capture/kills:

April 18, 2016: Abu Saif, ISIS “war council member” (joint Kurdish Peshmerga/U.S. special forces raid); unnamed individual also snagged from battlefield in separate op, also south of Mosul.

March 25, 2016: Haji Imam al-Qaduli (In a raid).

Mid-February 2016: Abu Dawud, ISIS' chemical weapons chief.

In late May 2016, U.S. special operators were allegedly photographed in northern Syria by Agence France-Presse, in an incident that caused headaches at the Pentagon. That uproar hinged more on Kurdish militia patches reportedly adorning American troops uniforms than anyone's surprise that special operators were busy fighting on the ground.

To Be Continued

Five-plus years of war in Syria have killed more than 400,000 people and displaced half of Syria's pre-war population—including 5 million refugees seeking a better life outside of their home country's borders.

An offensive on ISIS-held Mosul (with an estimated 1 million civilians) is expected to be months-long endeavor. An offensive on ISIS HQ in Raqqa, Syria, could take even longer.

Russia has even been accused of exacerbating the war in Syria, allowing the exodus of refugees to de-stablize Europe and the surrounding region further. Despite its claims to have entered Syria to carry out airstrikes against ISIS, most observers say Russia's role in the Syrian war has been largely to degrade rebel factions intent on the downfall of the Assad regime.

Western nations have focused the lion's share of their effort on defeating ISIS. But even if the group is defeated, what comes next for Syria is yet to be decided as President Bashar al-Assad vowed in early June 2016 to liberate "every square inch of land" inside Syria.

Key determination to come: Whether any semblance of unity can be achieved among more moderate and less jihadist and Islamic revolutionary opposition groups.

Many by now have been radicalized by so many months of unmitigated violence—violence which U.S. officials have warned will take “generations” to stabilize.

Overview | Small Arms | Tanks | Artillery | Airpower (Syrian) | Anti‑Aircraft Weapons | Barrel Bombs | Chemical Weapons | Airpower (Non‑Syrian) | Cruise Missiles | Suicide Bombers | Advisors