Update(1555ET): IDF Spokesman Rear Adm. Daniel Hagari has said ground and tank forces have at this point surrounded Gaza City. “Our troops have completed the encirclement of Gaza City, the center of Hamas activity,” he said in a late Thursday (local) press conference. The IDF has further announced the deaths of “130 terrorists” in the latest battles.
But Hamas' significant network of tunnels continues to plague IDF troops, given the ability for Hamas mounting successful ambushes from hidden holes in the ground, which the group has been keen to boast about, such as in the following…
Defense Minister Yoav Gallant has said he is preparing “unique solutions” to destroy the vast network of tunnels. “We have unique solutions to reach all the tunnels and dismantle them underground; we are ready to do it,” he said Thursday while addressing a combat engineering unit.
“We will reach everywhere, and then the terrorists will have two options: either die in the tunnel or come out. And there, either die from the fire of our forces or surrender unconditionally,” he said. Some prior reports suggested Israel could be planning to inject poison gas or nerve agents into the tunnels, but others dismissed these somewhat fantastical reports as not credible or even possible.
There's also the likelihood that releasing gas into tunnels would kill any Israeli and foreign hostages being held there. Dealing in such large quantities of chemical weapons or nerve gas on an active battlefield would also of course be highly dangerous for the very troops trying to deliver them into the tunnels. And its another question entirely whether enough could be pumped in to be effective across a wide underground network, considering the tunnels stretch for many miles.