Heavy machinery is seen on the Israeli side of the border with Gaza Thursday, Sept. 8, 2016. Israeli defense officials on Thursday said the government has begun work on a massive underground barrier along the border with Gaza meant to block Hamas militants from tunneling into Israel. The project is the hallmark of a huge effort Israel to halt the Hamas tunnels, which military officials have identified as a strategic threat. During a 2014 war, Hamas militants managed on several occasions to make their way into Israel through their tunnel network, though they did not reach nearby civilian areas. (AP Photo / Tsafrir Abayov)