The Israeli Defence Force (IDF) claimed that it discovered the biggest Hamas tunnel in the Gaza Strip on Sunday. A video was released by the Israeli military showing a white crib near a hole with descending spiral steps. In an official statement, the army said that the underground passage was part of a wider branching network that spread over four kilometres and came within 400 metres (1,300 feet) of the Erez border.EXPOSED: The biggest Hamas terrorist tunnel discovered.This massive tunnel system branches out and spans well over four kilometers (2.5 miles). Its entrance is located only 400 meters (1,310 feet) from the Erez Crossing—used by Gazans on a daily basis to enter Israel for work… pic.twitter.com/RcjK5LbvGL— Israel Defense Forces (@IDF) December 17, 2023Why is so special about the tunnelThe multimillion-dollar construction project was led by Mohamed Yahya, brother of Hamas chief Yahya Sinwar, who is believed to be the mastermind of the October 7 attacks.The intricate honeycomb of passageways has a comprehensive infrastructure, including drainage systems, electricity, ventilation, sewage facilities, and a communication network, complemented by rail systems. The tunnels construction has reinforced concrete walls and a compacted earth floor, with a secure entrance consisting of a metal cylinder with 1.5-centimeter-thick walls.Israeli army footage, reportedly filmed by Hamas, reveals the construction process, involving a small vehicle being driven into the tunnels with a temporary warehouse filled with pre-cast concrete, and workers using crude power tools to dig beneath the earth. The army disclosed the discovery of a substantial cache of weapons stored within the tunnel, intended for use in attacks against Israel.Root cause of the WarThe military action follows Hamass surprise attack on southern Israel on October 7, resulting in approximately 1,140 casualties, predominantly civilians, and the taking of 250 hostages, according to Israeli figures. In response, Israel launched a widespread campaign to dismantle Hamas, involving intense bombardment and a ground invasion of the Gaza Strip.