The Prime Minister has come out swinging at Australia over its decision to revoke the citizenship of a woman detained at the Turkish border, who reportedly attempted to enter from Syria.
Legally the woman's citizenship sits with New Zealand but Ardern said she would continue to raise the issue with Australia.
The 40-year-old leader said Australia had "abdicated its responsibilities" by unilaterally cancelling the citizenship, forcing New Zealand to shoulder the responsibility for the woman, who has not lived in New Zealand since she was 6.
Ardern said she has expressed her concerns to Australian Prime Minister Scott Morrison and that the two countries should be working more closely on these types of cases involving dual nationals.
He says we should just leave it to Turkish justice system to deal with her.
Turkish authorities said on Monday that three New Zealanders, including a woman alleged to be a member of Islamic State, have been caught trying to enter Turkey illegally from Syria. She was accompanied by two small children. Later that year she was informed Australia had revoked the woman's citizenship.
Ardern also urged Australia to consider the welfare of the woman's children.
"I understand the New Zealand Government has some issues with that".
"I will finally add: If the shoe were on the other foot, we would take responsibility, that would be the right thing to do". That's my job. And it's my job as the Australian Prime Minister to put Australia's national security interests first.
Mr Morrison, speaking at a press conference in Canberra an hour later, said it was his job as the Australian prime minister to "put Australia's national security interests first".
"Australia's interest here is that we do not want to see terrorists, who've fought with terrorist organisations, enjoying privileges of citizenship that I think they forfeit the second they engage as an enemy of our country".
"The legislation that was passed through our parliament automatically cancels the citizenship of a dual citizen where they've been engaged in terrorist activities of this nature".
"What's on my mind is the concept of country's responsibilities for the people they have helped rear". She travelled to Syria on an Australian passport. "We know that young children thrive best when surrounded by people who love them". She was however born in New Zealand, a country she left at the age of six.
She said the woman had lived in Australia since she was six years old before departing for Syria on an Australian passport.
It also raised a question around New Zealand's capability to deradicalise someone such as the woman in Turkish detention, and the financial burden that would fall on the Islamic community to support that, she said.
Reporters in the press gallery said the normally even-tempered leader was "visibly furious".
It was work the Chief Coroner should undertake as part of the inquiry into the Christchurch shootings, she said.