A 15-year-old British citizen has admitted to inciting an Islamic State-inspired terrorist plot at an Australian military ceremony in April, making him the youngest person to be convicted of terrorism in Britain, The Wall Street Journal reports.
The teenager, who is too young to be identified under British law, pleaded guilty to inciting terrorism via video link at London’s central criminal court Thursday.
He conceded that he encouraged an 18-year-old Australian, Sevdet Besim, to murder police officers on Anzac Day in April, an annual celebration commemorating the Australian and New Zealand Army Corps' World War I battle in Gallipoli.
British security officials thwarted the attack and detained the young man in early April after catching on to his communication with Mr. Besim. Counterterrorist officers in Melbourne also arrested five other teenagers linked to the plots.
The young boy, who was 14 at the time, had sent thousands of instant messages to Besim through encrypted messaging service Telegram over a 10-day period in March, the BBC reports.
According to prosecutors, the teenager encouraged Besim to run down police officers with a car and behead them with a knife before shooting others. An earlier court hearing revealed messages in which the British teenager told Besim to get "machetes" and to "sharpen as hard as u can," The Wall Street Journal reported.
In preparation for the attack, prosecutor Paul Greaney said, "The defendant sent Sevdet Besim a message that read, 'suggest you break into someone's house and get your first taste of beheading.'"
"Sevdet Besim responded to say that this seemed 'a little risky' and that aspect of the preparations appears then to have drifted away," added Greaney.
Prosecutors in the UK dropped a second charge against the British teenager, inciting terrorism overseas, while authorities in Australia charged Besim and another Melbourne teenager, Harun Causevic, with conspiring to commit a terrorist act.
According to The Associated Press, Besim and Mr. Causevic were under investigation because of their contact with Numan Haider, an 18-year-old who stabbed two Melbourne police officers and was subsequently shot dead last September.
An Australian terrorism task force had monitored Mr. Haider for months over what police considered troubling behavior, including waving what appeared to be an ISIS flag at a shopping mall.
The court was told that both Besim and the convicted teenager supported ISIS, the BBC reports.
The two men arranged the plot by texting through encrypted-messaging service Telegram, which was launched in 2013 as a secure alternative to WhatsApp, Line, and other messaging applications.
Telegram’s self-destruct feature allows users to set a timer for deleting messages without leaving a trace on any device. Though its secretiveness has been disputed, it has raised security concerns.
Encrypted messaging applications "make it much harder – and sometimes impossible – to obtain ... key evidence about terrorists or other criminals," reports the Journal.
In January, British Prime Minister David Cameron proposed banning secure messaging applications like Telegram unless they install backdoors to allow government spying. President Obama supported his suggestion.