A 15-year-old British boy has pleaded guilty to inciting terrorism by encouraging others to kill police officers during a war memorial ceremony in Australia. The boy, who can't be named because of his age, was arrested in northwest England in April. He was detained after Australian police arrested five teenagers on suspicion of plotting an ISIS-inspired attack at an Australian and New Zealand Army Corps Day ceremony in Melbourne. Prosecutors say the British youth sent thousands of instant messages to Australian suspect Sevdet Besim, including one saying "suggest you break into someone's house and get your first taste of beheading." Prosecutors on Thursday dropped a charge of inciting beheading. The teen, who was 14 when he was arrested, will be sentenced on Sept. 3.