In an exclusive interview, homeland security secretary Michael Chertoff said sources of radioactive and biological materials must be properly secured "at all costs". He warned terrorists are actively seeking to acquire such materials. Mr Chertoff said he did not think a weapon of mass destruction, like a biological or nuclear bomb, was a danger that could be just months away. ... His comments echo those of the British Home Secretary Jacqui Smith, who told Sky News last year that intelligence suggested terrorists were trying to get their hands on materials and know how to make a dirty bomb.

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