Analysts say the nuclear ambitions of Iran are likely to top the new cabinet's security agenda.
In an apparent reference to that effect, Mr Netanyahu said the biggest threat to Israel and the world came from "the possibility of a radical regime armed with nuclear weapons".
He further stressed the issue in comments given to a US magazine shortly before he was sworn in.
"You don't want a messianic apocalyptic cult controlling atomic bombs," he said
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in reference to Iranian President Mahmoud Ahmadinejad's belief in the imminent return of a Shia Islamic messianic figure, the Mehdi.