(JNS) Israel’s military has started to pump seawater into Hamas’s terror tunnels, part of an operation to destroy an underground network dubbed “the Gaza metro,” U.S. officials briefed on the matter say.

Flooding tunnels with seawater from the Mediterranean is one of several methods the IDF is employing to destroy the underground network, The Wall Street Journal reported on Wednesday, Dec. 13.

At the start of the month, IDF Chief of Staff Lt. Gen. Herzi Halevi said of the possibility of pumping seawater: “Any means which gives us an advantage over the enemy, deprives it of this asset, is a means that we are evaluating using.

“We are working—going from one tunnel to another, placing weapons there, and using a range of means to destroy this infrastructure, including through new ways soon,” said Halevi. “There is no place where Hamas will be free from IDF’s offensive capabilities.”