The Trump administration said Monday that the University of Pennsylvania violated Title IX by letting a transgender swimmer compete on the school’s women’s team and enter into women’s facilities. It gave Penn 10 days to voluntarily resolve the violations,

The US Department of Education’s Office for Civil Rights ruled Monday that the University of Pennsylvania violated Title IX guarantees against sex discrimination when it allowed a transgender woman to compete on its women’s swimming team.

The U.S. Education Department wants Penn to strip swimmer Lia Thomas of awards and apologize to female swimmers. The school has said it followed NCAA and Ivy League policies.