Judge rules UN diplomat's daughter in ISIS is not US citizen

US President Donald Trump waves to reporters. REUTERS/Leah Millis

A judge on Thursday agreed with US President Donald Trump's administration that an Alabama woman who joined ISIS was not an American citizen, leaving her and her toddler son in limbo in Syria.

Reggie Walton, a federal judge in Washington, agreed with the government that Hoda Muthana's father was still a diplomat when she was born, making her ineligible for US citizenship, her lawyer said.

The lawyer, Christina Jump, said she was waiting to read the ruling and that the Constitutional Law Centre for Muslims in America, which is representing Ms Muthana, 25, would look at further options.

The US grants citizenship to virtually everyone born on its soil and it is extremely difficult to revoke citizenship.

But as Ms Muthana's became more prominent, Mr Trump tweeted that she was not a US citizen and would not be allowed to return.

US Secretary of State Mike Pompeo later said Ms Muthana's father had been a diplomat representing Yemen at the UN, meaning his daughter was never a US citizen even though she travelled to Syria on a US passport.

She appeared to burn that passport in a propaganda message.

Ms Jump stressed that the judge based his ruling on the issue of diplomatic immunity.

"The court did not base its ruling on a tweet by the president, or by any supposed proclamation made by any official," she said.

"US citizenship cannot be revoked by tweet or any other form of social media, and today's ruling does not change that."

Ms Muthana was raised in Hoover, Alabama, a prosperous suburb of Birmingham, and says she was brainwashed through her smartphone by messages from ISIS.

In Syria, she was active on social media and married three foreign fighters, all of whom died in combat.

Ms Muthana says she has reformed and is willing to face prosecution in the US, where she wants to return for the sake of her son, aged 2.

"Anyone that believes in God believes that everyone deserves a second chance, no matter how harmful their sins were," she told NBC News from her displacement camp.

"I did not support the ISIS beheadings from day one. Until now I do not support any of their crimes and suicide attacks."

The US has repatriated several Americans but not Ms Muthana.

The court case comes as the US struggles to persuade European allies to repatriate their fighters from Syria.