Tunnel systems stretching from Gaza into Israel are used by Hamas and militants for weapons and warfare. During recent months Israel bombed and sealed off three tunnels, but the Israeli army says there's still an entire underground network inside the strip. CGTN's Stephanie Freid gained access to a tunnel on the Gaza-Israel border and brings us this report.

STEPHANIE FREID GAZA-ISRAEL BORDER "I'm inside one of the tunnels that the IDF blew up - it's about a kilometer and a half long and you've got about six meters here above me so it's very narrow. Not one of the more sophisticated tunnels that they've unearthed. "It's one of three in the last months that the IDF has discovered blown up the tunnels are generally used to transport weapons, bring in goods to Gaza but also to infiltrate inside Israel. The idea is to carry out hits on the Israeli population." Some are very sophisticated. They're big enough for motorcycles to go through small vehicles. We've been in one that had electricity running through it so again, this is less sophisticated. "What is Israel doing to counter the building of tunnels by Islamic Jihad and Hamas they're now building a sixty-five kilometer long underground barrier with a fence on top of it basically to cut tunnels so that no tunnels can be built. "That's going to cost just under one billion dollars and it's expected to take two years. By 2020 the IDF is hoping to finish construction on that. "How does that measure up with what Islamic Jihad and Hamas are building? It takes tunnel builders in Gaza about one day to build ten meters and if you add that up it takes about three months for one kilometer of tunnel to be built." What does the IDF say in terms of future threats?

JONATHAN CONRICUS, IDF SPOKESPERSON GAZA-ISRAEL BORDER "Inside Gaza there's basically a city beneath a city with tens and even hundreds of kilometers of underground facilities. About the terror tunnels penetrating into Israel: A positive step today but by no means the end of the story."

STEPHANIE FREID GAZA-ISRAEL BORDER "Complimentary to the barrier wall, Israel is also implementing underground sensors" Stephanie Freid, CGTN, on the GAZA-ISRAEL BORDER.