From December of 2021:
Israel announced on Tuesday the completion of a massive barrier around the besieged Gaza Strip, above and below ground, which took three and a half years to finish.
The project includes a sensor-equipped underground wall, a counter-measure developed after Hamas used tunnels to blindside Israeli troops during their 2014 offensive against the enclave.
Israel went public with the project, which also includes an above-ground fence, a naval barrier, radar systems and command and control rooms, in 2016.
Israel's defence ministry said the barrier, which includes hundreds of cameras, radars and other sensors, spans 65km and that 140,000 tonnes of iron and steel were used in its construction,
"The barrier, which is an innovative and technologically advanced project, deprives Hamas of one of the capabilities it tried to develop," Israeli Defence Minister Benny Gantz said, according to a defence ministry statement.
The ministry said the project's "smart fence" is more than six metres high and its maritime barrier includes means to detect infiltration by sea and a remote-controlled weapons system.
The ministry did not disclose the depth of the underground wall.
Israel has maintained a crippling blockade of the Gaza Strip since 2007, which critics say amounts to a collective punishment of the impoverished enclave's two million residents.
Israel prevents the importing of materials and equipment into Gaza and has imposed strict restrictions on exports, leading to a state of "paralysis" in several sectors of Gaza's economy.
https://www.middleeasteye.net/news/israel-gaza-barrier-completed-announced