For the most hawkish of hawks, there's no nuke so good as a shiny, bells-and-whistles new nuke. And if you look at the fine print of the latest budget request for the US Department of Energy, it's clear that these birds of prey have been busy of late.

Any proposal to build new nuclear weapons is highly controversial — and would require the express permission of the US Congress. Yet in its projections for future years' spending, the 2005 energy department budget request is trying to sow the seeds of such developments. These projections call for “subsystem tests and a full system test” of a nuclear bomb proposed to vaporize deeply buried bunkers and other ‘hardened’ targets. Further on, one can find plans to rehabilitate old nuclear testing ranges in Nevada and to build a facility to mass-manufacture plutonium triggers for detonating hydrogen bombs.

This activity is geared towards what the budget describes as the “stockpile of the future” — which, if a paper authored by four nuclear-weapons scientists at the Los Alamos National Laboratory in New Mexico is anything to go by, could feature an arsenal of mini-nuclear weapons (B. L. Fearey et al. Comp. Strategy 22, 305–324; 2003). The authors argue that such weapons would deter rogue states from developing subterranean stores of chemical and biological weapons. But in describing the bombs as causing “reduced collateral damage”, the paper raises the spectre of ‘usable’ nukes — a concept that causes the colour to drain from the cheeks of arms-control advocates.

Senior officials deny that there are any concrete plans to develop new weapons — merely “paper studies” to assess future options (see page 455). But seasoned observers see the current budget request as an attempt by the hawks within the Bush administration to pursue their new nukes agenda. These officials are backed by a minority of weapons scientists for whom life has lost meaning since their cold-war heyday, when they were given huge amounts of money to pursue the nuclear arms race with the Soviet Union.

This agenda is already damaging US national security. Russian politicians have responded with statements about developing next-generation strategic weapons. And if the United States and Russia start pursuing mini-nuclear weapons, it doesn't take much imagination to see that other countries, perhaps India and Pakistan, may follow suit. In an era in which the primary security threat seems to be from terrorism, the proliferation of portable nuclear weapons can't be a good idea.

Against this security background, America's nuclear-weapons scientists don't need to design new bombs to get back on the front lines of national defence. Many of them, for example, are members of top-secret nuclear search teams that watched over the New Year's celebrations in New York, Washington and other US cities this past winter. Others are working with the Department of Homeland Security to build detectors for ports and border crossings that can sniff out the faintest hint of radiation. And those working on stockpile-stewardship programmes continue to support global stability.

These noble efforts will be undermined by the plans of a nostalgic few. Physicists who care about arms control, and officials in the Bush administration who don't share the hawks' enthusiasm for new weapons, should unite to nip these nuclear ambitions in the bud before they make the world even more dangerous than it already is.