Israel is intensifying development of the Arrow 3 anti-ballistic missile system, it emerged this week.

Senior defence official Aviram Hason said at a Tel Aviv conference that the system was being fast-tracked and hinted that this was to deal with the Iranian threat. He said that the system could deal with threats from "outer ring" countries, meaning states that do not share borders with Israel.

There is enthusiasm among defence analysts about the level of defence it could give from long-range missiles. "To say we are 100 per cent protected will not be true, but I think, yes, close to that," said Uzi Eilam, senior research fellow at the Institute for National Security Studies, the non-governmental research centre where Mr Hason made his revelation.

Mr Eilam said that the system "could give defence to any country that is targeted by long-range missiles".

He expects the Arrow 3 to handle incoming missiles from more than 2,000 km away, and believes that it could deal with non-conventional was well as conventional warheads. "There are different types of missiles, but missiles are missiles, and the fact that there are chemical or nuclear warheads would not necessarily affect the capability of Arrow 3."

But Martin van Creveld, Jerusalem-based author of more than 20 books on military history and strategy, is less convinced about Arrow 3's capability. He said that people should be "very, very cautious" before formulating expectations for it.

He stressed: "There is no absolute security." He said that there are many variables that will determine its capability, and argued that, even if the system works well, its effectiveness will depend on Israel's supply of missiles, and "much will depend on luck".

The revelation about Israel fast-tracking Arrow 3 this week came as a defence tender published by the American government let slip classified Israeli plans to build an important military installation - apparently an Arrow 3 launch base - at Tal Shahar in central Israel. It contained secret building plans.

Mr Eilam did not believe that the leak would prove detrimental to Israel. "All in all, the Americans make sure that leaks of potential damage will not be made," he said.

Dr van Creveld said that US officials might have actually thought the leak beneficial. "They probably have their reasons for doing it - maybe they wanted to warn Iran or deter Syria."