I was under the impression the technology to identify underground stuff was pretty cheap.
The article indicated this tunnel was entirely inside Gaza and was likely used by militants for storage, staging, etc. Israel focuses on locating tunnels that cross the border, not ones that are nearly half a kilometer behind it.
Watch as it turns out to be another tunnel they made
This is the best summary I could come up with:
That day, militants used a rocket-propelled grenade to break past the portion of wall close to the Erez crossing and stormed the base, killing at least three soldiers and kidnapping some back to Gaza, the army said.
It was one of several places along the border wall where militants easily blew past Israel’s security defenses, entered Israeli territory and killed around 1,200 people and took about 240 others hostage.
The unprecedented attack triggered a devastating war that has raged for more than 10 weeks and claimed more than 18,000 lives in the Hamas-ruled Gaza Strip, according to Palestinian health officials.
He added that the entrance, a circular cement opening leading to a cavernous passageway, was located under a garage, hiding it from Israeli drones and satellite images.
While the military was aware that Hamas had an extensive tunnel network, Dinar said they didn’t think the militants would be able to carry out their plans for a large-scale attack.
The Erez crossing, a fortress-like facility that processed the movement of Palestinians into Israel for work, medical care and transit to neighboring Jordan, held great symbolic value for Hamas.
The original article contains 793 words, the summary contains 187 words. Saved 76%. I’m a bot and I’m open source!
