TEL AVIV — Israel has so far set modest aims for its ground invasion of Gaza: to restore sustained quiet for Israelis and to destroy the network of secret tunnels that Islamic militants have dug under its borders.
"Restoring sustained quiet" could mean anything, but the issue of the tunnels is critical for Israel. Militants, who use the tunnels to emerge inside Israel and surprise Israeli soldiers and civilians, are a massive threat to daily life in communities surrounding Gaza.
Dozens of these tunnels are believed to exist, and they can be sophisticated. Some boast concrete walls and ceilings, electric lighting, radio communications, sub-tunnels running off to the sides, and many are replete with booby-traps in case Israeli forces enter them.
The geography of the region is perfect for tunnels. The land in most of the border areas is composed of sand fossilized with sea shells, and earth. There are no massive rock formations to cut through. So one man with an electric or pneumatic jackhammer could advance four to five yards a day, one former officer in the army’s geology unit said.
Militants dig straight down, sometimes as deep as 20 meters, then burrow up to two miles into Israel, and emerge in the woods, or in an open area, and wait to attack.
Israel has roomfuls of soldiers — mostly female conscripts aged between 18 and 20 — staring at monitors showing pictures from cameras all along the border. It was one of these women who on Thursday spotted about 13 heavily armed Palestinians emerging from a hole inside Israel, only a couple of hundred yards from kibbutz Sufa.
She quickly alerted her officer, who alerted his superior, who in turn called in the coordinates — and within seconds a rocket was fired at the tunnel entrance. The gunmen, possibly having seen a drone overhead, had already scurried back into the hole. Five seconds after the last militant slipped back into the ground, the rocket hit. The fate of the gunmen was unclear.
Israeli government sources say it was this thwarted tunnel attack, plus the heavy rocket barrage from Gaza that followed the five-hour humanitarian pause in the fighting, that provoked Prime Minister Benjamin Netanyahu into giving the order to invade. Goal No. 1: eliminate the tunnel threat.
To cope with the military push, Israel is to call up another 18,000 reserves. That makes 68,000 called up in the current conflict so far — considerably more than the 30,000 called up during the three-week invasion of Gaza in 2009, and the 50,000 called up in the 2012 fighting which did not result in a ground invasion.
The army says it could take 10 to 14 days to solve the tunnel problem. And the longer the fighting goes on, the greater the chances for this conflict to escalate.