Israel Defence Minister Yoav Gallant said that Israel has entered a new phase in the war as IDF sent tanks & other ground forces into Gaza.
In the past, Israel has also named Gaza Strip's tunnel system as 'Metro' and as per AP, Hamas has a massive underground network in Gaza.
In 2021, Yihyah Sinwar, the head of Hamas in Gaza claimed that they have 500 km of tunnels even though Israel destroyed 100 km of it.
Israel military has known of Gaza tunnels threat since at least 2001 as at that time Hamas h used tunnels to detonate explosives under Israeli border.
Israeli military destroys these tunnels though remote-controlled robots. They go inside with masks, oxygen and other things