Shamima Begum joined the Islamic State radical "with her eyes open", authorities lawyers person told a tribunal.
Ms Begum's British citizenship was removed aft she travelled to IS-controlled Syria aged 15.
Challenging the decision, her ineligible squad reason she was trafficked to Syria for intersexual exploitation.
But astatine a proceeding connected Thursday authorities lawyers, defending the decision, said it did not substance Ms Begum was lone 15 erstwhile she travelled there.
Sir James Eadie KC, connected behalf of the government, said: "You could good person been radicalised and manipulated astatine an property erstwhile you are vulnerable... but nevertheless nevertheless unfortunate it mightiness beryllium you are present a risk.
"You tin inactive beryllium a hazard of mounting disconnected a weaponry successful London oregon successful Manchester… adjacent if you person been trafficked astatine a young age."
The lawsuit is being heard astatine the Special Immigration Appeals Commission (SIAC), which has akin lasting to the High Court, and tin perceive nationalist information grounds successful concealed if necessary.
Sir James told the tribunal: "The appraisal made by the Security Service [MI5] was that [Ms Begum's] question was voluntary and demonstrated her determination and committedness to aligning with Isil."
Isil is different sanction for IS, meaning "Islamic State successful Iraq and the Levant".
He went on: "She travelled for the intent of aligning with Isil, and erstwhile successful Syria she did successful information align with Isil.
"The appraisal is that she did that with her eyes open.
"The ideology of Isil and their uncompromising brutality had been wide covered successful the media."
Ms Begum's lawyers reason the past Home Secretary Sajid Javid should person taken into relationship she was trafficked to Syria for intersexual exploitation purposes erstwhile making his determination successful 2019.
She near her location successful London successful February 2015 with her 2 schoolhouse friends Amira Abase and Kadiza Sultana. Within days she was successful IS-controlled territory successful Syria and was soon joined to an IS fighter.