New York, New York - Sophie Turner is taking legal action against Joe Jonas as she accuses the star of unlawfully keeping their two children in the US.

Since confirming their divorce on September 6, Sophie and Joe's split is taking another tense turn as the 27-year-old Game of Thrones alum sues her estranged husband over their two daughters.

Per TMZ, Sophie alleges that Joe is keeping their children in New York City despite their agreement to raise them in Sophie's native England.

In the legal documents obtained by The Messenger, the Dark Phoenix actor claims they mutually decided England would be the "forever home" for their 3-year-old daughter, Willia, and 1-year-old daughter, whose name has not been revealed.

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Sophie has stated that the Jonas Brothers frontman's "wrongful retention" of the girls began "on or about" September 20.

The suit also alleges that Joe "refused to return their daughters' passports" despite their agreed-upon plan to have them return to England on September 17. The children both reportedly receive their medical care across the pond and are "fully involved and integrated in all aspects of daily and cultural life in England."

Sophie also alleged in the legal documents that she found out about Joe's decision to file for divorce "through the media."

In the lawsuit, the Do Revenge star revealed that their split "happened very suddenly," which coincides with the pair's loved-up appearance at the Jonas Brothers' Yankee Stadium shows just last month.

Despite the new revelations, Sophie and Joe released a joint statement saying that the divorce was a mutual decision shortly after the news broke in the media.

"There are many speculative narratives as to why but, truly this is a united decision and we sincerely hope that everyone can respect our wishes for privacy for us and our children," the former couple said.