A number of children of foreign fighters, some orphans, are in Syrian refugee camps.
The mothers of these children have issued pleas in recent weeks for their safe return to countries of their citizenship.
The threat of a resurgent IS
As the presence of IS in Syria is at a low ebb, a number of wives of foreign fighters, dubbed 'IS brides', have pleaded for the countries which gave them citizenship to give refuge to their children.
Prime Minister Scott Morrison said on Thursday that while he is considering removing the citizenship of Australian IS bride Zehra Duman, her children are a different matter.
"This will be a very complex case and Australia will make decisions consistent with our national security interests," he told reporters.
"Obviously the issue of the children involved is also a very sensitive one. The children can’t be held responsible for the crimes of their parents."
Deakin University professor of Global Islamic Politics Greg Barton said the children of IS fighters are in a very vulnerable situation.
"When it comes to their children we have an obligation, a human obligation and a legal obligation to help young human beings who are innocent of the sins of their parents; and who happen to have a tie to citizenship to our country."
He said it is in Australia's best interests to secure their return and avoid the possibility of their re-integration into the terrorist network.
"It is not just a question of humanitarian or legal obligations. It is a question of how best to defeat this ongoing threat of terrorism," professor Barton said.
"We need to be very careful now that with all this hard work of defeating Islamic State that in turning away, we're not quick to assume the job is done. Because the smoldering embers we've seen before with this organisation and others that flames can erupt again."
Number of stateless people estimated to be 12 million
The United Nations children's agency, UNICEF, said all children of foreign fighters have a right to "a name, an identity and a nationality”.
"Children need legal-aid and support to ensure no child is denied their right to citizenship," UNICEF said last week.
The UN estimates the number of stateless people globally right now could be 12 million. The body wants the number reduced to zero by 2024 to ensure people are not left without access to education and health.
2500 children of foreign fighters in camps: Save the Children
Aid agency Save the Children has called for more than 2500 foreign children living in Syrians camps to repatriated with their family to their countries of origin.
The families - representing 30 nationalities - have suspected links with IS.
The US-backed Kurdish militia say they are a week away from pushing out the last remnants of IS from Syria. The development has increased the urgency of what to do with the families of foreign fighters.
Save the Children says since the start of this year, 560 foreign families, involving more than 1,1000 children have entered Syrian refugee camps.
"All states whose nationals are trapped in Syria must take responsibility for their citizens," Save the Children's Syria representative, Sonia Khush, told Reuters.
"While some states have begun to do so, many countries – including several European countries – have yet to take steps to ensure the safety of the children and their families."
In a report, Save the Children estimate one in five children — or 420 million total — live in conflict zones.
Case of British IS bride triggers global debate
Some of the so-called IS brides were recruited by IS as children and are now giving birth to infant in the camps. Some of the children, now adults, face prosecution upon returning to their country of origin.
Greg Barton said the children and mothers should be brought back to Australia rather than be allowed to be re-absored into IS.
"We need to try to get to these kids, assess them, give them immediate care and then bring them back to Australia.
"I would also suggest that we need to bring our citizens who fought [for IS], to bring them to face justice [in Australia] to ensure that they are not a threat to us and the world by being able to roam the world at large."
19-year-old Shamima Begum from the UK gave birth last month, which triggered global debate based on fears that allowing her return would "open the floodgates" for other IS members.
The British government is facing a legal challenge from Ms Begum's family after deciding to remove her British citizenship to prevent her return.
But more than 400 British citizens “of national security concern” are believed to have returned from conflicts in Syria and Iraq.