America is preparing to upgrade and renew parts of its own nuclear arsenal as it accuses Iran of trying to develop nuclear weapons. Critics believe the upgrades could lead the US to breach the Treaty banning the testing of nuclear weapons. Since the project will probably involve replacing technology that originated in the Sixties, watchdogs are concerned the US might be inclined to test the newer systems and, therefore, breach the 1996 Comprehensive Test Ban Treaty.

Of more concern is President George Bush's dedication to developing a new breed of "bunker-buster" nuclear weapon, designed to penetrate toughened underground defences. Critics say the plan reveals the administration's hypocrisy and undermines international efforts to persuade other countries not to develop weapons. Last week, it was revealed that the Defence Secretary, Donald Rumsfeld, had sent the Department of Energy a memo requesting that it set aside funds to resume a study to examine the development of a bunker-buster bomb. The study had been halted last year after Congress removed its funding.