This is true, and to be fair, the Syrian "civil war" wasn't really a civil war. Insurgents flooded in from Iraq, Jordan and Turkey en masse which is why the ISIS/Rebel (same thing really) strongholds and territories are along these borders. Foreign governments like US, Israel, Saudi Arabia, Qatar, UAE, Turkey all poured billions into various terrorist factions, and shipped in heavy weaponry. Russia, Iran, Hezbollah all got involved on the side of Assad.