Five teenage girls who had shown an interest in going to Syria have been barred from travelling abroad by a judge at London's High Court.
The girls - two aged 15 and three aged 16 - were made wards of court, removing their passports and banning them from leaving England and Wales.
It comes after Tower Hamlets local authority, in London, raised concerns.
Last month, three girls from an east London school travelled to Syria, where it is feared they joined Islamic State.
Making the order, Mr Justice Hayden directed that the girls were not identified, and also ordered the removal of the passports of a number of adults involved in their care.
There was evidence to suggest family members in the case had not been full and frank with social services, the judge said, and that the girls were becoming more radicalised.
"It seems to me that that must have been known to the parents and they deliberately did not share it with the authorities who were keen to protect these vulnerable young girls," Mr Justice Hayden added.
He said he made the order following evidence that, in at least one other case, young girls had travelled on passports belonging to family members.
Police believe Shamima Begum and Amira Abase, both 15, and Kadiza Sultana, 16 - who all left their London homes last month - are now in Syria.
Shamima used the passport of her 17-year-old sister to leave the UK, police have said.
The three girls were friends and pupils at Bethnal Green Academy, based in the London borough of Tower Hamlets.
A fourth girl from the same school, Sharmeena Begum, 15, from Bethnal Green, left about two months before the three girls.
All four teenagers are thought to be in Raqqa - the Syrian city where IS has its headquarters.
A 16-year-old boy whose two elder brothers were killed fighting in Syria's civil war was barred from travelling abroad at a hearing on Tuesday.
The teenager was also made a ward of court following an application from Brighton and Hove City Council.
Mr Justice Hayden - who also ruled on the earlier case - said the risk to teenagers travelling to Syria was "as grave as it can be".
"As I said early this week in another case, and I repeat it in this, sometimes the law has to intervene to protect these young people, ultimately from themselves.
"Therefore I am satisfied there is evidence of sufficient cogency and the evaluation of risk is such as to justify the orders sought."
A spokesman for Tower Hamlets Council, which raised concerns about the girls, said: "We have not taken this step lightly but we came to the conclusion that it was in the best interests of the young people involved to take this course of action."