A pressing tactical challenge for Israeli military forces in Gaza is finding and clearing a massive network of tunnels where hostages are believed to be held. Retired Army Maj. John Spencer, chair of urban warfare studies at the Modern War Institute, joins "Elizabeth Vargas Reports" to discuss what he says is essentially a "city under a city." #Gaza #tunnels #hostages Anchor Elizabeth Vargas delivers the biggest stories, without bias or opinion. Watch "Elizabeth Vargas Reports" every weeknight at 6p/5C on NewsNation. #VargasReports NewsNation will host the final Republican primary debate on Dec. 6 at 8 p.m. E.T. The debate will be aired and streamed live on all NewsNation platforms. Not sure how to find us on your TV? Use our ChannelFinder app: joinnn.com NewsNation is your source for fact-based, unbiased news for all America. More from NewsNation: newsnationnow.com Get our app: trib.al/TBXgYpp Find us on cable: trib.al/YDOpGyG How to watch on ...