Under the scheme, developed by the Joint Chiefs of Staff but yet to be ratified by Donald Rumsfeld, the Defence Secretary, commanders would be able to request permission from the President to use nuclear weapons in a variety of scenarios. According to The Washington Post, one scenario is of an enemy that is using, or "is about to use", WMD against US military forces or the civilian population. Another is where nuclear weapons could be used against biological weapons that an enemy was close to using, and which could only be safely destroyed by nuclear weapons and their after-effects.
In practice, the strategy would update existing guidelines, drawn up in 1995 under the Clinton administration. It would fit in with plans mooted by the Pentagon to develop a new generation of nuclear weapons, specifically designed to attack enemy bunkers holding WMD, which could be buried deep underground.
Congress has thus far declined to provide funds for a study into the so-called "Robust Nuclear Earth Penetrator", not least because of criticism that such a move would make a mockery of US-led efforts to prevent nuclear-weapons proliferation, and make it more, rather than less likely, that such weapons would be used.
The Pentagon document argues that proliferation has already made it more likely that nuclear weapons could be used. It claims that some 30 nations have WMD programmes - not to mention terrorists, or "non-state actors", some of them acting with state sponsorship.