A nine-month moratorium on underground nuclear testing, imposed last September by the US Congress, is due to expire on 1 July, and President Bill Clinton is under mounting pressure to make clear his position on the issue. Britain is affected directly because it conducts tests in the Nevada desert.
As Mr Clinton ponders the future of the programme, he has come under fierce attack from the former president Ronald Reagan for cutting back too quickly on defence spending. In a speech on Saturday, Mr Reagan suggested that America's leaders 'open their eyes and take a long hard look' at remaining security risks. He particularly lamented the end of Star Wars, which he launched in 1983.
The testing ban enacted by Congress last year stipulated that there should be no testing until July this year, after which the US government would be permitted to carry out just 15 tests in a period lasting until September 1996. From that date, however, a comprehensive ban would come into effect.
Mr Clinton is believed to have rejected arguments put to him by some nuclear scientists and military experts that he should seek an amendment to the law allowing the US to pursue a limited number of low-level underground nuclear blasts beyond 1996. Many in the administration believe such a move would undermine efforts to dissuade countries with nuclear aspirations, such as North Korea and Iran, from pursuing weapons development programmes.
It remains possible that Mr Clinton could go a step further and forgo even the opportunity to conduct 15 tests between July and 1996, thus keeping the current moratorium in place. Such a step would be popular with the administration's own Arms Control and Disarmament Agency and many in Congress.
Britain, however, has made plain its strong desire to resume testing from July. Any attempt to close that window would draw strong diplomatic protests from London. But the British government has so far taken no firm position on whether it could accept a ban from 1996.
Senior officials in Mr Clinton's National Security Council discussed the issue last Friday and reportedly reached no conclusions. But the President will have to make his position clear before the 1 July date for the temporary resumption of testing.
Colouring the debate is the administration's propensity towards scaling back America's military ambitions. This was characterised by the decision, announced last week, to scrap the Star Wars programme. 'The Star Wars era is over,' the Defense Secretary, Les Aspin, said, pledging to redirect funding primarily towards missile defence systems for use in regional conflicts, like the Gulf war.
Formally known as the Strategic Defense Initiative (SDI), the Star Wars programme was meant to lead to the deployment into space of missile interceptors to provide the US with a kind of space-shield against surprise attack. But during ten years of development, at a total cost of dollars 32bn ( pounds 21bn), the system never came close to becoming reality.