[lbo-talk] Ways to close Gaza's tunnels -- and why they all won't quite work

Michael Pollak mpollak at panix.com
Mon Jan 19 04:57:34 PST 2009


http://www.slate.com/id/2208889?wpisrc=newsletter

Friday, Jan. 16, 2009

Slate.cm

Holey War

How to close the Gaza tunnels.

By William Saletan

[Actually thankfully by his interns, Jennifer Akchin and Gage Newman,

who googled up the information that constitutes 98% of this article.]

In the air, planes, helicopters, and drones patrol and fire at will. On

the ground, Israeli troops advance while Hamas lies in wait. But the

ultimate battleground isn't visible from the sky or on your television

news. It's underground.

Gaza is riddled with tunnels. Some are for smuggling; others are for

transporting weapons; others are for hiding or ambushing Israeli

troops. The crucial passageways--400 to 600, by recent estimates--run

from Gaza to Egypt, circumventing the closed border. That's how Hamas

gets parts and material for the missiles it fires into Israel. Any deal

to end the current fighting has to include "an effective blockading" of

that border, "with supervision and follow-ups," according to Israel's

prime minister. To stop the war--and to keep it stopped--you have to

figure out how to stop the tunnels.

But how? Here are some of the options.

1. Buffer zone. Israel used to control a 300-meter strip between Gaza

and Egypt. That wasn't enough to stop Gazans from tunneling under it to

Egypt. But what if the strip were thicker? Would that raise the cost of

tunneling, or the probability of a collapse somewhere along the

passage, enough to deter diggers? Israeli hawks want a buffer zone

three kilometers thick, which would make tunnel excavation much more

difficult, expensive, and time-consuming. Lately, the Israeli Defense

Forces have dropped leaflets urging Gazans along the border to leave

their homes--an attempt, some experts believe, to use the war to widen

the buffer zone. But good luck getting Hamas, the Palestinian

Authority, or European intermediaries to hand over three kilometers of

south Gaza, much less remove the inconvenient residents from their

homes.

2. Wall. Instead of thickening the old buffer zone, how about deepening

it? Years ago, Israel tried a concrete-iron wall that extended 10 feet

underground. A nice try, but fairly useless, since the tunnels went at

least 20 feet underground. Then, just more than a year ago, two

high-ranking officials from the U.S. Defense and State Departments went

to Egypt with a proposal to build a new barrier, including "piles

driven deep into the earth." But even if you extend a wall far enough

underground, tunnelers can dig through it.

3. Moat. Maybe, instead of burying a solid barrier that could be dug

through, we should make the barrier hollow and fill it with water. That

way, anyone trying to dig through would--well, let's just say you

wouldn't want to be there when it happened. This was such an intriguing

idea that Israel tried it several years ago, soliciting bids for a moat

four kilometers long, 100 meters wide, and 80 feet deep. Estimated

cost: $250 million. Israel scrapped the plan because the water would

come from the sea and might contaminate Gaza's groundwater. But the

idea keeps coming back. Two years ago, Israel broached it again, and

Egypt considered it. The U.S. officials who went to Egypt a year ago

raised it again. Even the president of the Palestinian Authority has

lobbied Egypt to do it.

4. Trench. If a moat is too dangerous to Gaza's groundwater, how about

digging the same trench but leaving it empty? That would expose anyone

who tried to get from one side to the other. Israel tried this idea,

too, soliciting bids for a trench five kilometers long and 50 to 80

feet deep. The IDF even bought a 100-ton trench digger from Texas. The

trench was supposed to be only 25 meters wide. But Israel dropped the

plan because, at a minimum, it would have required demolition of 200

Palestinian homes. That's a problem, but less of a problem than the

demolitions required for a buffer zone. And given the current

alternative--smuggling, bombardment in Israel, and war in

Gaza--everyone but Hamas might decide the demolitions are an acceptable

price to end the fighting.

5. Ground-penetrating radar. If a barrier is too hard to build or can't

do the job, maybe sensors can help. That's how the United States

detects tunnels and digging along its border with Mexico. According to

a presentation last month by the Army's Engineering, Research, and

Development Center, we've used several methods: magnetic, electrical

resistivity, ground penetrating radar, electromagnetic, and seismic.

All of these methods involve sending waves into the ground and

identifying anomalies on the rebound.

Some of the methods look unsuitable for Gaza. But what about

ground-penetrating radar? This was a favorite tool along the Mexican

border until tunnelers discovered its limits: It can't see deeper than

one meter in wet dirt or 15 meters (49 feet) in sand, dry soil, or

rock. At that point, all the tunnelers had to do was find the right

terrain and dig under the range of GPR, making it obsolete. Good news:

The ground around Gaza is dry and sandy. Bad news: Gaza's tunnels

already go 50 to 60 feet deep. So GPR may not be up to the job.

6. Electromagnetic gradiometry. This might solve the depth problem.

Originally developed for the demilitarized zone between North and South

Korea, it detects underground voids by discerning slight anomalies in

electromagnetic or gravitational fields. Companies that sell EM

gradiometers try to keep the range secret, so they don't become

obsolete like GPR. One published account estimates their outside range

at 150 feet. That's deeper than any known Hamas tunnel. Still, it

leaves the problem of administration. The IDF abandoned its strip on

the Gaza-Egypt border four years ago because it was too hard to defend.

Who's going to operate the machines?

7. Drone-operated gradiometry. Here's an idea: Put the tunnel sensors

on unmanned aerial vehicles. Supposedly this has been tried

successfully at least once on the U.S.-Mexico border. A year ago, the

Department of Homeland Security told Congress that DHS was

"experimenting with UAV mounted digital electromagnetic gradiometers."

A presentation from the DHS Science and Technology Directorate depicts

a team of drones (see Slide 27) using gradiometry to sniff out tunnels.

The drones selected for the assignment are already available, "fully

autonomous," can fly for 10 hours, and have "a data link range of up to

22 nautical miles." Or the IDF could modify its own drones to do the

job. So Israel wouldn't need sitting-duck ground forces to monitor

tunnels and diggers. It could hunt them from the air.

8. Automatic sensors. If you don't want drones along the border, you

could try "acoustic" or "seismic" sensors. These require no operators

and, according to a research paper that accompanied last month's Army

presentation, can detect digging or movement in a tunnel even in

conditions that "confounded GPR and electromagnetic techniques." The

Army has field-tested a network of buried acoustic sensors in Iraq,

with "overwhelming success," the paper reports. This network, which the

Army now calls the Tunnel Activity Detection System, consists of buried

sensors ("geophones") that are connected by an underground cable and

transmit data to an operations center "via a satellite uplink."

Theoretically, the geophones could be buried along the Egypt-Gaza

border, and the operations center could be in Tel Aviv.

The U.S. Army Corps of Engineers is already working with Egypt on such

a system. Recently, the United States allocated $23 million to Egypt

for tunnel sensors. Two months ago, Ha'aretz reported that the corps

was teaching Egyptian soldiers how to find tunnels using "instruments

that measure ground fluctuations." Last week, the Washington Post said

the corps was helping Egypt find tunnels with "sonar equipment."

Apparently, what worked in Iraq is now being tried to Gaza.

Unfortunately, Israel doesn't trust Egypt to police the tunnels. Could

Israel's defense industry build a similar system? It already has. Sonic

Lynx, a firm based near Tel Aviv, advertises "an array of seismic and

acoustic sensors deployed in the ground" that relay data "to a remote

control and display station, where security personnel can view the

classification of the threat together with its accurate location."

Meanwhile, Electro-Optics Research and Development, a Haifa company

that specializes in acoustics and seismology, has developed seismic

antennas that can identify underground threats. Sonic Lynx recently

lobbied the IDF to put its sensors under the Israel-Gaza border. In

fact, Israel already has experience using acoustic sensors to hunt

tunnels along Gaza's border with Egypt.

9. Statistical bombing. Having failed to block the Egypt-Gaza tunnels,

Israel is now bombing them from the air and shelling them from the sea.

Some tunnels were picked out beforehand--the Israeli Air Force hit 40

in a single night--but in other cases, according to Yedioth Ahronoth,

the IAF "dropped at 10-meter intervals 600 kg bombs with timing

devices, which 'statistically' hunt the hidden tunnels." If Israel

can't get a deal to block the tunnels with sensors or a barrier, it

might have to resort to "statistical" bombing again. That could mean a

bombing campaign along the border every three to six months--the length

of time it takes diggers to complete new tunnels. An ugly prospect, to

be sure. But not as ugly as what's going on right now in Gaza.

(Human Nature thanks Slate interns Jennifer Akchin and Gage Newman, who

tunneled through the Internet to bring back the parts that were

assembled to make this article.)



More information about the lbo-talk mailing list