The U.S. State Department fired a diplomat for concealing a romantic relationship with a Chinese woman alleged to have ties to the Chinese Communist Party.

This marks the first known dismissal under a ban introduced late last year prohibiting U.S. personnel, contractors, and their families in China from engaging in such relationships.

The decision followed a review by President Trump and Secretary of State Marco Rubio, who emphasized a zero-tolerance policy for actions undermining national security.

The diplomat and his girlfriend were featured in a secretly filmed video posted online by James O’Keefe, the Associated Press has reported.

Chinese officials declined to comment on the case, calling it a domestic U.S. issue and warning against ideological smears.