Last weekend, former Israeli Ambassador to the U.S., Michael Oren, offered his take on why Hamas will not return all the hostages it holds.

Brig. Gen. Yehuda Fox, who leads the army's Gaza division, on a tour of Hamas and Islamic Jihad tunnels discovered and destroyed in recent months, near the Israeli kibbutz of Kissufim, Feb. 2, 2018.

Flooding the tunnels may also imperil the 137 hostages still being held in Gaza by various groups, which have traditionally used the underground networks to store valuable assets, ...

The Israeli military said Tuesday that it had begun pumping water into the vast network of tunnels beneath Gaza, which Hamas has used to launch attacks, store weapons and imprison Israeli hostages.

Israeli forces have started flooding Hamas tunnels in Gaza with seawater pumped from the Mediterranean in an effort to destroy the underground network, according to news reports filed Wednesday.

Brig. Gen. Yehuda Fox, who leads the army's Gaza division, on a tour of Hamas and Islamic Jihad tunnels discovered and destroyed in recent months, near the Israeli kibbutz of Kissufim, Feb. 2, 2018.