US nuclear weapons are among the most sophisticated scientific devices on the planet. Through the years of the cold war, US designers labored to make warheads that were frighteningly powerful, yet so small that as many as 10 could fit on top of a single missile.
Now the nation's nuclear bureaucracy believes the time has come to start replacing these complex weapons with simpler ones. Last week the Department of Energy announced the selection of a design for a new Reliable Replacement Warhead, meant to be safer, easier to manufacture, and more robust than current models.
If approved by Congress, development of this warhead could set the course for the US nuclear arsenal for decades to come.
But when it comes to nuclear weapons, does the US really need to swap Cadillacs for Fords? Critics say the current arsenal is reliable enough – and that any new US bomb would send the wrong message to potential nuclear proliferators such as Iran and North Korea.
"Other countries are going to look at this, and they are going to keep their warhead development and production options open," says Daryl Kimball, executive director of the Arms Control Association.
The current US nuclear stockpile is the legacy of decades of scientific and military competition with the Soviet Union. Driven by what they felt was a need to counter an existential threat to the nation, US scientists perfected methods of extracting enormous explosive yields from weapons that were also as small as possible.
That meant designing weapons with little margin for engineering or manufacturing error. For example, the W-88 submarine-launched warhead is crammed into a dart-thin reentry vehicle to decrease its susceptibility to wind and thus increase its accuracy. The W-76, an older Navy weapon, has a uranium radiation case the thickness of a soda can. That case must remain intact for a microsecond upon detonation if the warhead is to fully explode.
Throughout the cold war, US scientists also treated plutonium as a scarce and valuable resource and made weapons whose fissile hearts were relatively small.
But today's geostrategic world is vastly different than the one of decades ago. The US has no need to counter a large nuclear adversary move for move.
"We still have the same missiles, but they carry far fewer warheads, so there's no particular premium on making those warheads light. And I'm spending money to get rid of plutonium, not conserve it," said Linton F. Brooks, then-administrator of the Department of Energy's National Nuclear Security Administration, in a discussion on the future of nuclear weapons last year.
According to current and former US officials, the US can take advantage of change in the world and to redesign existing warheads so that they have more margin for error, are easier to manufacture, and may be secure against terrorists if they are ever stolen.
Enter the Reliable Replacement Warhead (RRW). The RRW design project began three years ago. Per congressional order, it is supposed to produce only replacements for existing warheads – not to create additional warheads for new missions such as attacking underground bunkers. The US has an arsenal of about 6,000 deployed warheads and has previously said it would reduce the number to 1,700 to 2,200 by 2012.
On March 2, the National Nuclear Security Administration announced the selection of a design from Lawrence Livermore and Sandia National Laboratories for RRW development. Under the program, Navy submarine-launched weapons would be the first warheads replaced.
US officials indicated that the Lawrence Livermore design beat out a competitor from the Los Alamos National Lab in large part because it was based on older designs that have already been proven effective in underground nuclear tests.
The US has maintained a moratorium on nuclear tests since 1992. It has signed, but not ratified, the Comprehensive Test Ban Treaty, which bans explosions in all environments for military or civilian purposes.
The chosen design "builds on the successful scientific accomplishments of our Stockpile Stewardship Program, which helps to maintain our nuclear weapons without underground testing," said Thomas P. D'Agostino, NNSA acting administrator, on March 2.
Over the next year, US lab scientists will put together cost estimates and an engineering and production plan that Congress will be able to consider next year, Mr. D'Agostino added.
The point of this effort is not to start a new arms race, said the NNSA acting administrator. But the new weapon design has already drawn opposition from key members of the new Democratic-controlled Congress.
Rep. Peter Visclosky (D) of Indiana, the chairman of the House Appropriations subcommittee on Energy and Water – which has jurisdiction over nuclear development funding – says the administation needs to set a coherent policy for the future of nuclear weapons before it starts building new warheads.
Sen. Dianne Feinstein (D) of California, a member of the Senate Apppriations panel that will consider RRW funding this year, remains adamantly opposed to a new design.
In a statement, Ms. Feinstein said that potential proliferators such as Iran and North Korea would look at the program and see hypocrisy on the part of the US.
"The minute you begin to put more sophisticated warheads on the existing [delivery systems], you are essentially creating a new nuclear weapon," Feinstein said.
Some critics consider the very name of the effort to be a misnomer. To call something a "reliable replacement" is to imply that the thing which is to be replaced is unreliable – but that's not the case, notes Mr. Kimball of the Arms Control Association.
Studies have shown that, with current maintenance programs, the existing stockpile will be reliable for decades, says Kimball.
But is it worth spending billions to add a minute additional increment of reliability, especially when the production of a new weapon might inevitably increase pressure for the resumption of nuclear tests?
It is also arguable, Kimball adds, that new warheads can be certified as safe and reliable without new test explosions.
"With all the associated geostrategic costs, it is not worth it," he says.