The Israeli military has begun pumping water from the Mediterranean Sea into Hamas' tunnel network, the Wall Street Journal reported Tuesday, quoting US officials familiar with the operations. The move, still in its early stages, is one of several techniques Israel is using in its operation to eliminate the Hamas terror group. A spokesperson for Israel's Defense Minister Yoav Gallant (Likud) declined to comment to WSJ , telling the news outlet that "tunnel operations are classified." The Wall Street Journal report quoted the US officials as saying that Israel has installed seven industrial pumps, and began the process around when it added the last two pumps to the initial five and conducted initial testing. The process is expected to last for several weeks, the report added. US officials have expressed doubts about the effectiveness or feasibility of flooding a complex estimated to include hundreds of kilometers of tunnels, and have pointed out that doing so could damage Gaza's agriculture and freshwater supply. Israel is reportedly still examining whether or not flooding the tunnels is a realistic strategy, although Israeli officials have thus far declined to comment on the operation. Related articles: 'I don't understand why Israel gave up Gaza' Terrorists in Syria threaten Israel Abducted soldier's mother: 'My son is wounded and forgotten' Gaza government declares Rafah region 'disaster zone' Hamas's underground tunnel network is one of the main challenges facing Israel's ground offensive and has allowed Hamas to continue to challenge Israeli control even in areas where the IDF has taken full control of the surface. Israel's commitment to destroying Hamas's military capabilities will mean destroying the vast majority of the tunnel network, where IDF troops have already found evidence of far-reaching infrastructure capabilities. The report states that the IDF has thus far attempted to minimize conflict underground, as doing so reduces the availability of fire support by aircraft, ships, and artillery. The IDF has instead used a wide variety of alternatives, including attack dogs, drones, engineering equipment, and liquid explosives to destroy the tunnels without engaging in combat within them. This evening, Defense Minister Yoav Gallant stated that the IDF was locating and destroying Hamas military infrastructure deep underground, as well as killing hundreds of terrorists in the effort.