LONDON (AP) — A British teenager was sentenced Monday to at least 16½ years in prison for plotting a bombing whose potential targets included an Elton John concert on the 15th anniversary of the Sept. 11 attacks.

Haroon Syed, who was arrested last year, had admitted planning terrorist acts at an earlier court hearing.

Passing sentence at London’s Central Criminal Court, Judge Michael Topolski said 19-year-old Syed had been intent on “carrying out an act of mass murder in this country.”

Sentencing Syed to life with no chance of parole for 16½ years, the judge said the young man had been “deeply committed to the ideology of a brutal and barbaric organisation that sought to hijack and corrupt an ancient and venerable religion for its own purposes” — the Islamic State group.

Prosecutors said Syed tried to buy weapons and explosives online from an extremist named “Abu Yusuf,” who was actually a series of British intelligence agents.

He said he was considering targeting London’s busy Oxford Street shopping district and searched online for potential locations, including an Elton John concert in Hyde Park on Sept. 11, 2016.

Defence lawyers said Syed had been vulnerable to radicalisation, especially after the arrest of his elder brother Nadir. Nadir Syed was sentenced last year to a minimum of 15 years in prison for plotting an Islamic State group-inspired beheading to coincide with Remembrance Sunday war commemorations.

Haroon Syed was arrested in September 2016. When police asked for the password to unlock his phone, he said: “Yeah, I.S.I.S. You like that?”