The opening was so small that CNN 's Wolf Blitzer -- no physical giant -- had to bend down to climb inside one of 30 or so Palestinian tunnels from Gaza to southern Israel . `` I guess the tunnel was built for relatively short people , because if you stand up you 're going to hit your head , '' Blitzer said of the almost two-mile concrete corridor about 45 feet underground where he reported from Monday . His visit , accompanied by the Israeli military , revealed conditions in the network of tunnels below Gaza that are a key issue in the current violent spasm between Hamas militants in Gaza and Israel . Originally built to avoid Israeli and Egyptian checkpoints into Gaza , the tunnels have been vital supply lines for Palestinians in Gaza . Now the snaking underground routes increasingly get used for attacks in Israel . Israeli Prime Minister Benjamin Netanyahu launched a ground assault on Gaza this month intended to destroy the tunnel network , and Blitzer went into one of them so see what it was like . Cooler than the surface . So far down , the tunnel was surprisingly cool inside compared to the hot conditions on the surface , Blitzer noted . Stooped over , he walked along the concrete-encased pathway with wiring visible in some parts . The concrete came from Israel , as did the electric power Palestinians send down for lights in some parts , said Lt. Col. Oshik Azouli , deputy commander of Israel 's Southern Gaza Brigade . It took two years or more , progressing a meter or two a day , to extend the tunnel into Israel , according to Azouli . `` It 's pretty secure , this concrete , '' Blitzer said . `` They spent a lot of effort building this tunnel . '' The tunnel ended near a kibbutz in Israel , Azouli said , adding its purpose was to attack people on the collective agriculture community . Used for attacks . Later Monday , the Palestinian representative to the United States told Blitzer the tunnels originated to get around the blockade of Gaza , but take on another role in conflict . `` Factions in Gaza are utilizing them to target the Israeli military , especially at times of conflict , '' Maen Rashid Areikat said , adding : `` They want to be creative about how to respond to any attacks . and probably also take initiative . '' A series of Hamas attacks via tunnels on Israeli soil escalated Israel 's response in the current violence . The method of attack , in which militants spring out unexpectedly from underground , has raised fears among Israelis living near Gaza . `` They are a strategic danger , '' Israeli government spokesman Mark Regev said of the tunnels later Monday , telling Blitzer it was `` unacceptable '' to have Hamas attackers `` just pop out of the ground on our side of the frontier to murder and kidnap . '' However , Palestinian parliament member Mustafa Barghouti called the tunnels a defensive tactic against repeated Israeli invasions in recent years . `` These tunnels are nothing but a primitive way of trying to defend themselves , '' he told Blitzer . 'Lower Gaza ' Israeli military officials refer to the tunnels as `` Lower Gaza . '' They are n't new . Hamas used one in 2006 to capture Israeli soldier Gilad Shalit and take him into Gaza . He was held captive for five years until a deal was struck for his release in exchange for more than 1,000 Palestinian prisoners . During its incursion into Gaza , Israel 's military has so far found scores of different access shafts leading to about 30 tunnels . It says it destroyed about half , but expects to find more . Blitzer said Israel wants to remove the tunnels from the equation before agreeing to a cease-fire with Hamas .
Tunnels unacceptable to Gaza ; a defense tactic to Palestinians . Built to beat the Israel blockade , the tunnels now get used to launch attacks . Hamas 's Gilad Shalit describes the underground paths of CNN . Israel wants to destroy the tunnel network .