Congress moves closer to approving a new generation of small tactical nuclear weapons, despite the warnings of arms control experts.
The US used nuclear weapons against Japan to end World War II
The US House of Representatives looks set to approve funds for the research and development of a new generation of small tactical nuclear weapons which could be used to attack deep bunkers holding weapons of mass destruction.
The House Armed Services Committee is voting the money as part of the $400bn defence authorisation bill which will be reported out on Tuesday.
Last week, the Senate Armed Services committee approved the money in a closed vote.
The move would overturn a ten-year ban on such developments, and still has to be approved by the full House and Senate.
We have tried for 50-plus years to make these weapons unthinkable, and now we're talking about giving them a
tactical application - it's a dangerous departure.
Democratic Senator Jack Reed
The shift of policy has been sought by the Pentagon since last summer, when it began to develop plans to reshape the US nuclear arsenal to take account of the new doctrine of pre-emption.
Fear of proliferation
Democrats warned that it would make harder to contain the spread of nuclear weapons.
"This is a major shift of policy," said Senator Carl Levin of Michigan.
"It makes a mockery of our argument around the world that other countries - India, Pakistan - should not test and North Korea and Iran should not obtain (nuclear weapons)."
But the chairman of the committee, Republican Senator John Warner, said that it was a prudent step to defend the US against enemies.
"America has had a ban on this research since 1993, yet that has done nothing to stop other countries from seeking to acquire
nuclear weapons," he pointed out.
Under the Bush administration, the US has signed a strategic arms-control deal with Russia, but it has abrogated the anti-missile defence treaty and has expressed doubts about the comprehensive test ban treaty.
New nuclear weapons
US strategic planners believes that the new tactical nuclear weapons are essential to meet to threat of terrorism and weapons of mass destruction, and says they could be used against chemical or biological weapons facilities and nuclear bunkers buried deep underground.
But arms controls advocates say that the plans could undermine US efforts to limit nuclear proliferation at a time when North Korea, among others, seems intent on developing nuclear weapons.
"We have tried for 50-plus years to make these weapons unthinkable," Democratic Senator Jack Reed said.
"And now we're talking about giving them a
tactical application. It's a dangerous departure."
The new weapons under consideration include low-yield tactical nuclear weapons, which yield under five kilotons, less than one-third of the first atomic bomb used at Hiroshima, and a "robust nuclear earth penetrator", designed to bury deep into the ground before exploding.
Potential targets could include North Korea, which is suspected of hiding its nuclear production sites in areas carved out of mountains.
The new earth-penetrating bomb would be based on the one remaining US tactical nuclear weapon, the B61, with a strengthened nose cone to allow it to penetrate frozen soil or rocks.
The even smaller nuclear weapons, with yields of under five kilotons could be used against above-ground weapons production facilities.
They would take longer to develop, and might require underground testing - something that the Congressional committees also authorised.