The Bush administration is eager to start work on a new nuclear warhead with all sorts of admirable qualities: sturdy, reliable and secure from terrorists. To sweeten the deal, officials say that if they can replace the current arsenal with Reliable Replacement Warheads, they probably won’t have to keep so many extra warheads to hedge against technical failure. If you’re still not sold, the warhead comes with something of a guarantee — that scientists can build the new bombs without ever testing them. Let the buyer beware. While the programme has gotten very little attention here, it is a public-relations disaster in the making overseas. Suspicions that the US is actually trying to build up its nuclear capabilities are undercutting Washington’s arguments for restraining the nuclear appetites of Iran and North Korea.

While experts debate whether the labs can really build a weapon without testing it, the more important question is whether any president would stake America’s security on an untested arsenal.

America would be much safer if the president focused on reducing the number of old nuclear weapons still deployed by the US and the other nuclear powers. The new Congress should stop this programme before any more dollars are wasted, or more damage is done to America’s credibility.