I'm sure I read somewhere the other day that DARPA have been devoting a vast amount of effort and expense to drilling technology, and recently tested a fairly compact drill that can bore a 15cm diameter hole through solid granite at several hundred feet a minute. But now I can't find any reference to it.
If I were an Iranian atomic scientist, working in an underground facility, now might be time to start worrying.
If I were an Iranian atomic scientist, working in an underground facility, now might be time to start worrying.