Israeli Prime Minister Benjamin Netanyahu decried a "very heavy price" of the Gaza war following the deaths of Israeli soldiers in combat over the weekend. The AP news agency reported the death toll has climbed to 15, citing an Israeli military announcement.

"Let's be very clear: this will be a long war," Netanyahu said on Sunday. 

Separately, the Israeli military said it had completed the dismantling of Hamas' underground headquarters in northern Gaza, part of an operation to take down the vast tunnel network used by the organization.