Ahmed Muthana, the father of Nasser Muthana, a 20-year-old student from Cardiff who has appeared in an unverified Isis recruitment video, said that police didn't do enough to stop his younger son Aseel from travelling abroad with his brother.
He said that police told him the 17-year-old had "obtained another passport."
ITV News Correspondent Lewis Vaughan Jones spoke to Ahmed Muthana in Cardiff today:
Leaders of a Cardiff mosque, attended by 3 young men who are now fighting in Syria, say they had nothing to do with their radicalisation.
The Home Secretary has told ITV News that young women have left Britain to fight for the extremists group ISIS in Syria and Iraq.