U.S. Defense Threat Reduction Agency is creating a tool to bore through the earth to reach underground facilities. The Massive Ordinance Penetrator (MOP) can bore through up to 60 feet of concrete (depending on the type). But it is rumored that Iran is developing an ultra-hard concrete, challenging the Pentagon to develope a stronger tool.
Using some German engineering, these tools are able to detect voids and soil densities. Additionally, the Strategic Technology Office of DARPA is investing in sensor technologies “that find, characterize and identify facility function, pace of activity, and activities in conjunction with their pre and post attack status.”