Decoded, this means nuclear devices with that produce small amounts of radiation, earth-penetrating weapons to attack underground bunkers, larger devices with greater radiation effects and weapons to destroy chemical and biological agents.

The meeting, called the "Stockpile Stewardship Conference", grew from a re-assessment of US nuclear strategy in the post-Cold War era.

This "Nuclear Posture Review" was sent by the Pentagon to Congress in December 2001.

More flexible

It basically said that there had to be a switch away from the old nuclear deterrent - using long-range bombers, missiles and submarines - to a more flexible approach based more on defences such as the anti-missile system now being developed and small devices yet to be made.

The major weapons systems have to be reduced anyway under a treaty with Russia, cutting deployed nuclear warheads to between 1,700 and 2,200 by the year 2012.

At the time of the review, the US Assistant Secretary for International Security Policy, J D Crouch, said: "Today we have a very different situation (from the Cold War). We have a situation where the United States may face multiple potential opponents, but we're not sure who they might be. There are multiple sources or potential sources of conflict."

Multiple sources of conflict are leading to multiple sources of weapons.

'Earth penetrator'

The review identified the earth penetrator as one element of the new arsenal:

"With a more effective earth penetrator, many buried targets could be attacked using a weapon with a much lower yield than would be required with a surface based weapon.

"This power yield would achieve the same damage while producing less fallout (by a factor of ten to twenty).

"For defeat of very deep or larger underground facilities, penetrating weapons with large yields would be needed to collapse the facility," it said.

A report from the House of Representatives subcommittee on national security said in February 2003: "The president should have options - the options of conventional forces, of precision conventional weapons and of nuclear weapons that are capable of holding all targets at risk."

Opposition

There has been an anti-nuclear demonstration at StratCom this week by the Los Angeles Study group, the organisation which leaked the agenda.

And numerous anti-nuclear pressure groups have criticised the mini-nuke plan.

In Britain, Ben Miller, a spokesman the Campaign for Nuclear Disarmament, told BBC News Online: "It is shocking, disgusting and disgraceful that US defence department officials are meeting in the very week of the anniversary of the bombing of Hiroshima and Nagasaki in which over 110,000 people died.

"The US is pressing the world to get rid of nuclear weapons yet is doing the exact opposite itself."

In the United States, Robert Musil, executive director of Physicians for Social Responsibility, said: "Why in the world would we move towards manufacturing small nuclear weapons and then expect that no one will ever try to steal, beg or borrow one and use it against us?"

Other panels at this week's conference will consider the issue of how to maintain the US nuclear stockpile in working order without being able to carry out live tests.

The US has observed a moratorium on testing since 1992 and is developing a computer-based simulation programme instead.

It is not known however if these computer tests will do the job.

So there will be an examination at the meeting as to whether live testing will be recommended again.