Government leaders and analysts have long attempted to trace the source of Syria's weapons stock, knowing little more than that Russia backs President Bashar al-Assad's regime. But a new study by a Washington-based nonprofit may have tracked down the port where the regime's arms originate. The study reports that over the past two years, a high volume of traffic has passed between Ukraine's Oktyabrsk port and Syria's main Mediterranean ports. The ships included small vessels flying Syrian and Lebanese flags and large tankers known to have shipped arms in the past. The larger ships in particular are linked to a network of businesses with ties to the Russian government.