HONG KONG: The first minors convicted under Hong Kong’s national security law were Saturday sentenced to detention in a training centre by a judge who said their calls to overthrow China’s government must be met with deterrence.

A 16-year-old girl and three 17-year-olds were members of a little-known pro-independence group that called itself “Returning Valiant” and promoted a violent uprising against China at street booths and on social media last year, the court heard.

They were charged with “conspiracy to incite subversion” under a sweeping national security law that Beijing imposed on the city to stamp out dissent after huge and sometimes violent democracy protests three years ago. On Saturday, judge Kwok Wai-kin said the defendants’ message could have turned peaceful demonstrators violent — even though he conceded there was no direct evidence of anyone being incited.

“Even if one person is incited, Hong Kong’s stability and residents’ safety could have been greatly harmed,” Kwok said. The four teens, which AFP has chosen not to name because of their age, all pleaded guilty last month alongside fellow defendant Kwok Man-hei, 19.

All five were sentenced to up to three years at a training centre, a rehabilitation-focused detention facility which can be a sentencing option for teens aged 14 to 20. In a previous hearing, prosecutor Stella Lo said the group spread its messages outside busy railway stations, gave press conferences and held online broadcasts over the span of four months.