On the surface, the competing fighters in Syria are fuelled by an overlapping mixture of ideologies and political agendas. Just below it, experts suspect, they're powered by Captagon.
A tiny, highly addictive pill produced in Syria and now widely available across the Middle East, its illegal sale funnels hundreds of millions of dollars back into the war-torn country's black-market economy each year, likely giving militias access to new arms, fighters and the ability to keep the conflict boiling, says the Guardian.
"Syria is a tremendous problem in that it's a collapsed security sector, because of its porous borders, because of the presence of so many criminal elements and organised networks," the United Nations Office on Drugs and Crime regional representative Masood Karimipour told Voice of America. "There's a great deal of trafficking being done of all sorts of illicit goods - guns, drugs, money, people."
A powerful amphetamine based on the original synthetic drug fenethylline, Captagon quickly produces a euphoric intensity in users, letting Syria's fighters to stay up for days, killing with a numb, reckless abandon.
"You can't sleep or even close your eyes," said a Lebanese user, one of three who appeared on a BBC Arabic documentary that aired in September. "And ... nothing can stop it."