REUTERS/Ibraheem Abu Mustafa
According to an article published by the Institute for Palestine Studies, at least 160 children died during the construction of the tunnels, which were made with 800 tons of concrete. In this latest conflict, they've been used on several occasions to kill soldiers inside of Israeli territory, a potential red line for the country's decision-makers.
Several journalists have entered the tunnels, including CNN's Wolf Blitzer. A YouTube video posted by the Shebab News Agency gives an especially jarring and intimate perspective on Hamas's tunnel network: a first-person view of one tunnel as it's being used in a Hamas ambush.
The video claims to document an attack on an Israeli army watchtower by Hamas fighters, and contains graphic content. The fighters in the video emerged from a tunnel complex, underscoring why Israeli leaders believe that their destruction is such a vital priority.
According to the Israeli newspaper Ha'aretz, the video depicts an attack near the border community of Nahal Oz in which five Israeli soldiers were killed.
We have highlighted the non-graphic segments of the video in the GIFs below.