LONDON (AP) — A 15-year-old British boy has been sentenced to at least five years in custody for organizing a terrorist plot to kill police officers in Australia.

Judge John Saunders said the teenager, who can’t be named because of his age, would only be released when he was no longer a danger to the public.

Prosecutors say the boy planned the Islamic State group-inspired attack from his suburban bedroom in Blackburn, northwestern England. He conspired with 18-year-old Australian Sevdet Besim to behead police officers at a war memorial parade in Melbourne.

The teenager, who was 14 when he was arrested in April, admitted inciting terrorism and is one of Britain’s youngest convicted terrorists.

Saunders said Friday it was “chilling” that a 14-year-old could become so radicalized that he wanted to kill.

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