I just saw that the Federation of American Scientists is reporting that Congress has asked the Departments of Defense and Energy to begin studying the feasibility of deploying low-yield ground penetrating nuclear weapons. The idea would be to use these to take out subterrian hardened targets, with an eye to countering threats from uppity third world nations.

These weapons are said to be able to limit collateral damage. But, the physics of the project suggests that it will be impossible to prevent a lot of highly-radioactive dust from being thrown into the local atmosphere. And this would blur the lines between conventional and nuclear warfare. Trouble.