Hamas had been digging tunnels in Gaza for decades. The Lebanese Shiite organization has used tunnels and underground bunkers since the IDF withdrew from southern Lebanon in 2000. Now there’s concern that Hezbollah has expanded its network of tunnels inside south Lebanon, to enable offensive infiltration into Israel. Benjamin Netanyahu said the Hamas cross-border tunnel network had the  ‘catastrophic’ potential of gunmen emerging into southern Israel near army positions, kibbutzim and settlements. Israeli communities on the Lebanese border have in the past reported hearing muffled sounds underground, which they believe indicate Hezbollah tunne-digging. Now, such reports are gaining new resonance and the Israeli security establishment is taking their concerns seriously. An article published on Hezbollah’s website cited that ‘security elements’ spoke of booby-trapped tunnels prepared over the past two years inside southern Lebanon, allowing fighters to move easily from place to place during battle. Last month, Hamas official Osama Hamdan said that the exchange of knowledge between Hamas and Hezbollah on Israel is ongoing.