SINGAPORE — The terrorism threat has grown more severe since the 9/11 attacks, especially with groups such as the Islamic State in Iraq and Syria (ISIS) widening their reach in radicalising people across age, gender and geographical boundaries, Deputy Prime Minister Teo Chee Hean said yesterday.

In particular, Mr Teo raised his concern that many ISIS fighters continue with the group’s violent agenda even after they return to their homelands.

“They could carry out attacks in their home countries, form their own terrorist group or join local and regional terrorist groups … they could also radicalise and recruit their countrymen to fight in Syria and Iraq, or to join their terrorist network,” said Mr Teo, who was delivering the opening address at the inaugural East Asia Summit Symposium on Religious Rehabilitation and Social Integration.