From the uproar in Israel and the defensiveness of Mr Olmert's supporters it looks very much like this was a mistake, or a "nuclear slip of the tongue" as some Israeli papers have described it.

But it probably serves Israel's interests to revise its long-held policy of "strategic ambiguity". For many years Israel was the only country outside the five declared nuclear powers to have built an atomic weapon. As such it deliberately wanted to maintain ambiguity about its status.

First, it wanted its enemies in the region to know that it had nuclear capability if threatened.

But it also wanted to keep the existence secret so that it did not fall foul of international action designed to halt the proliferation of nuclear weapons, particularly strict US laws which could have jeopardised billions of dollars in annual aid.

These circumstances have now changed. India, Pakistan and North Korea have also acquired nuclear weapons. Iran is moving close to building an atomic bomb. Arab states throughout the region are hastily launching civilian nuclear programmes which would at least give them the option of developing a nuclear weapons capability down the road.

Pakistan has not suffered much damage because of its nuclear weapons programme, mainly because the West needs its support in the War on Terror. India has just completed an important nuclear agreement with America. It is very unlikely that Israel would suffer any significant fallout if it made a public declaration. Most countries are now far more fearful of Iran and its potential threat to the region.

As a result, there is probably more sympathy than ever in the West for Israel to maintain a nuclear deterrent.

In Israel, where Mr Olmert's opponents have been calling for his resignation, it seems to matter politically.

Outside the world of Knesset politics, however, Mr Olmert was simply stating what everyone has known ever since 1986 when The Sunday Times published details of Israel's secret atomic weapons programme thanks to Mordechai Vanunu, a technician at the secret Dimona nuclear site in the Negev desert.

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