US President Donald Trump attacked 16-year-old climate activist Greta Thunberg, criticizing Time magazine for naming her Person of the Year.

Greta Thunberg became the symbol of the growing movement of young environmental activists after her weekly student strikes in Sweden and has gained a tremendous number of followers due to her ardent speeches during protests and conferences over the past year-and-a-half.

Trump tweeted the following: “So ridiculous. Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill!”