[ExI] Tunnels

[David Lubkin]

Israel and the United States have an interest in 
preventing tunnels in. Prisons and prison 
nations, like North Korea or the old East 
Germany, have an interest in preventing tunnels out.

Are there any credible technologies, either 
current or plausible future, that can stymie 
tunneling by wealthy, motivated opposition along 
ranges from (say) 10^2 to 10^6 meters —at least 
by anything less than a hypothetical shaped 
nuclear charge, MNT disassemblers, or the sort of 
large, expensive tunnel boring machine that is hard to obtain or conceal?

(Such a barrier appears in sf but I've never seen 
one described to the level of credibility.)


-- David.