The Bush administration is planning a secret meeting in August to discuss the construction of a new generation of nuclear weapons, including "mini-nukes", "bunker-busters" and neutron bombs designed to destroy chemical or biological agents, according to a leaked Pentagon document.

The meeting of senior military officials and US nuclear scientists at the Omaha headquarters of the US Strategic Command would also decide whether to restart nuclear testing and how to convince the American public that the new weapons are necessary.

The leaked preparations for the meeting are the clearest sign yet that the administration is determined to overhaul its nuclear arsenal so that it could be used as part of the new "Bush doctrine" of pre-emption, to strike the stockpiles of chemical and biological weapons of rogue states.

Greg Mello, the head of the Los Alamos Study Group, a nuclear watchdog organization that obtained the Pentagon documents, said the meeting would also prepare the ground for a US breakaway from global arms control treaties, and the moratorium on conducting nuclear tests.

"It is impossible to overstate the challenge these plans pose to the comprehensive test ban treaty, the existing nuclear test moratorium, and US compliance with article six of the nuclear non-proliferation treaty," Mr Mello said.

The documents leaked to Mr Mello are the minutes of a meeting in the Pentagon on January 10 this year called by Dale Klein, the assistant to the defense secretary, Donald Rumsfeld, to prepare the secret conference, planned for "the week of August 4 2003".

The National Nuclear Security Administration, which is responsible for designing, building and maintaining nuclear weapons, yesterday confirmed the authenticity of the document. But Anson Franklin, the NNSA head of governmental affairs, said: "We have no request from the defense department for any new nuclear weapon, and we have no plans for nuclear testing.

"The fact is that this paper is talking about what-if scenarios and very long range planning," Mr Franklin told the Guardian.

However, non-proliferation groups say the Omaha meeting will bring a new US nuclear arsenal out of the realm of the theoretical and far closer to reality, in the shape of new bombs and a new readiness to use them.

"To me it indicates there are plans proceeding and well under way ... to resume the development, testing and production of new nuclear weapons. It's very serious," said Stephen Schwartz, the publisher of the Bulletin of the Atomic Scientists, who added that it opened the US to charges of hypocrisy when it is demanding the disarmament of Iraq and North Korea.

"How can we possibly go to the international community or to these countries and say 'How dare you develop these weapons', when it's exactly what we're doing?" Mr Schwartz said.

The starting point for the January discussion was Mr Rumsfeld's nuclear posture review (NPR), a policy paper published last year that identified Russia, China, North Korea, Iraq, Iran, Syria and Libya as potential targets for US nuclear weapons.

According to the Pentagon minutes, the August meeting in Strategic Command's bunker headquarters would discuss how to make weapons to match the new policy. A "future arsenal panel" would consider: "What are the warhead characteristics and advanced concepts we will need in the post-NPR environment?"

The panel would also contemplate the "requirements for low-yield weapons, EPWs [earth-penetrating weapons], enhanced radiation weapons, agent defeat weapons".

This is the menu of weapons being actively considered by the Pentagon. Low-yield means tactical warheads of less than a kiloton, "mini-nukes", which advocates of the new arsenal say represent a far more effective deterrent than the existing huge weapons, because they are more "usable".

Earth-penetrating weapons are "bunker-busters", which would break through the surface of the earth before detonating. US weapons scientists believe they could be used as "agent defeat weapons" used to destroy chemical or biological weapons stored underground. The designers are also looking at low-yield neutron bombs or "enhanced radiation weapons", which could destroy chemical or biological weapons in surface warehouses.

According to the leaked document, the "future arsenal panel" in Omaha would also ask the pivotal question: "What forms of testing will these new designs require?"

The Bush administration has been working to reduce the amount of warning the test sites in the western US desert would need to be reactivated after 10 years lying dormant.

© Guardian Newspapers Limited 2003

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