Separation Fence Bad, Tunnels Bad

The separation fence is very bad. The Israeli Defense Forces claim that they have destroyed 80 tunnels to Egypt, over the years, possibly used for smuggling weapons into Gaza. The fence, above ground, is bad. But if the Israelis wanted to build an underground wall, to stop tunnels, on their side of the Egyptian border, and they didn't interfere with water mains or anything, then I don't see how that would be bad at all.