Sir: The decision to extend the Nuclear Non-Proliferation Treaty (NPT) indefinitely, taken by more than 170 states in New York this week ("Treaty bans spread of nuclear arms for ever", 12 May) is the correct one.
Not only does it outlaw the spread of nuclear weapons in perpetuity, it also creates the "best possible framework for further progress towards the disarmament goals of the Treaty", according to the UK's conference position paper.
However, this is no time to be complacent. Preventing the proliferation of nuclear weapons - and other weapons of mass destruction - requires constant vigilance and effort. For example, we need a more effective and better-resourced International Atomic Energy Agency. Is the current annual budget of about $200m really sufficient for the NPT's watchdog? Can Britain afford more than its present contribution of £8m?
Nor can we allow the arms reduction process to slacken. The nuclear weapon powers have agreed to "progressive and systematic" efforts to achieve complete nuclear disarmament. A strengthened NPT review process will monitor and assess progress towards that goal - preparatory meetings in each of the three years preceding a five-yearly review conference.
Britain need not regard this prospect with trepidation. Over recent weeks the British government has made a number of steps in the direction of nuclear restraint and disarmament. It is worth maintaining that momentum, rather than falling to any possible temptation to use one successful conference as an excuse to rest on one's laurels.
Indefinite extension of the NPT was secured in the expectation that nuclear disarmament will now be pursued with determination. If that expectation subsequently proves to be unfulfilled, the treaty's future could still be in doubt.