Days after a 16-year-old transgender athlete placed first in two events at the California state track-and-field championship, the Trump administration is threatening legal action and “large scale” fines.

The Justice Department gave California high schools one week to confirm that they will comply with the Trump administration’s stance on transgender athletes as the government takes aim at the state’s regulations allowing students to compete on the basis of gender identity.

The president posted Monday on social media that Gov. Gavin Newsom “fully understands, large scale fines will be imposed” following AB Hernandez’s participation in three events.