When police detained an Indonesian teenager accused of bombing his high-school campus in Jakarta in November, he had a life-size toy rifle inscribed with "welcome to hell" and the names of white supremacist mass killers. The Nov. 7 attack, which injured 96 people, may have been the first in the country inspired by white supremacists, but police fear it won't be the last.

At least 97 youths ¡ª the youngest just 11 ¡ª are being monitored after coming under the influence of content glorifying mass violence and white supremacists spread largely on messaging app Telegram, Indonesian police said in March.

At least two were planning acts of violence following the Jakarta bombing, according to the police.