The war in Syria has become a tangled web of conflict dominated by al-Qaeda veterans, hardened Iraqi insurgents, Arab jihadist ideologues and Western volunteers." On the surface, those competing actors are fueled by an overlapping mixture of ideologies and political agendas. Just below it, experts suspect, they're powered by something else: Captagon. A tiny, highly addictive pill produced in Syria and 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. A powerful amphetamine tablet based on the original synthetic drug known as "fenethylline," Captagon quickly produces a euphoric intensity in users, allowing Syria's fighters to stay up for days, killing with a numb, reckless abandon. "Syrian government forces and rebel groups each say the other uses Captagon to endure protracted engagements without sleep, [and] ordinary Syrians are increasingly experimenting with the pills," Reuters reported. One secular ex-Syrian fighter who spoke to the BBC said the drug is tailor-made for the battlefield because of its ability to give soldiers superhuman energy and courage. Another ex-fighter told the BBC that his 350-person brigade took the pill without knowing if it was a drug or medicine for energy. While Westerners have speculated that the drug is being used by Islamic State fighters, the biggest consumer has for years been Saudi Arabia. In 2010, a third of the world's supply - about seven tons - ended up in Saudi Arabia.