US officials say such planning is only normal
Senior American officials have been defending a document which reviews nuclear weapons options for the United States.
The document outlines scenarios in which nuclear weapons might be used against a number of countries.
Parts of the document - called the Nuclear Posture Review - were published in the Los Angeles Times. Secretary of State Colin Powell portrayed it as "sound.. conceptual planning" only, not a blueprint for any attack.
The seven nations mentioned - China, Russia, Iraq, North Korea, Iran, Libya and Syria - had or were developing weapons of mass destruction, he said.
Not a single nation, he went on, was being targeted by the United States on a day-to-day basis and the report was the kind of planning that the American people would expect.
Right to react
The same line was taken by the National Security Adviser Condoleezza Rice. She said that no one should be surprised that the United States was worried about the spread of weapons of mass destruction.
It had been long-standing American policy to reserve the right as to how to respond should some states use them.
Behind the arguments is a further move into the post-Cold War world. During the confrontation with the Soviet Union, the use of nuclear weapons was really only contemplated in a conflict with Moscow.
That prospect has gone, though Moscow's possession of large numbers of nuclear warheads still has to be considered by American planners.
Growing threat
But, now and increasingly in the future, the threat exists of not just nuclear weapons, but biological and chemical ones from a variety of sources around the world and the US military wants to position itself so that it can face these.
It is ready to contemplate going nuclear even in smaller scale conflicts than the one envisaged with the Soviet Union.
And it is also looking at the kind of nuclear weapons it might need. One example the report touches on is whether a nuclear bomb might be needed to destroy an underground stockpile of chemical weapons.