As Syrian rebels want to gain an advantage over Syrian regime forces, they have turned to Hamas for instructions on how to build terror tunnels.
Syrian rebels have built a 700 meter long terror tunnel in Mount Arbaeen, Syria, which they have rigged with 350 tons of homemade explosives, including TNT and C4. To learn how to build a terror tunnel, they turned to their “brothers” in Gaza.
Hamas responded by sending a video and clear instructions.
https://www.youtube.com/watch?v=gEf8SnP011w