Leading article: A foolish decision, made in haste

The Prime Minister's announcement that Britain's Trident nuclear deterrent is to be renewed was as disappointing as it was unsurprising. Whatever arguments Mr Blair marshalled yesterday to justify the spending of £20bn or so on new submarines, we find the arguments on the other side a good deal more compelling. The Trident system was conceived and built to combat a particular threat: that presented by the Soviet Union at the height of the Cold War. Today's Russia may not be the benign Western-orientated state we had hoped for after the collapse of the USSR, but it is not the threatening superpower of old either.

Today's strategic neighbourhood is quite different - and less predictable. The threats we face are from terrorism and global warming, and from countries that aspire to buck the international nuclear non-proliferation regime. North Korea makes no secret of its nuclear ambitions, and Iran wants to keep us guessing. Whether yesterday's announcement sends these countries a useful message is questionable. There was a chance here for Britain to set a new direction in the international debate: one that was about restraint rather than escalation. That opportunity has been lost.

The timing also smacks of politics. The Liberal Democrat leader, Sir Menzies Campbell, argued yesterday - and we agree with him - that there would have been merit in waiting until international security trends became clearer. There was no need to take any decision on Trident until the next Parliament at the earliest. The haste suggests a desire on Mr Blair's part to seal a part of his New Labour legacy by ensuring that Labour never retreats again into unilateralism: this is to play party politics with national defence.

Mr Blair's statement contained some concessions to his critics - most of whom sit on his own benches. The nuclear weapons budget, he said, will account for a fraction - 3 per cent - of the overall defence budget. Investment in new submarines will not be at the expense of conventional defence. The submarines will be built by British companies, in Britain. The number of warheads could be reduced from around 200 to 160 - rather less than the 50 per cent cut some had called for.

These, though, are details. They do not alter the principle, which is that Britain is set to modernise its nuclear capacity using money that could better be spent on other things, at a time when nuclear weapons may not be the best way of meeting the new threats to our national security. Parliament has been promised a vote next March. Regrettably, the extensive public debate that we should have had about the future of Britain's defence capability has been closed before it had properly begun.