President Donald Trump lashed out at 16-year-old climate activist Greta Thunberg on Thursday, a day after she was named by Time as its Person of the Year, calling her selection “ridiculous."

The Swedish teen has become a symbol of a growing movement of young climate activists after leading weekly school strikes in Sweden that inspired similar actions in about 100 cities worldwide. She has drawn large crowds with her fiery appearances at protests and conferences over the past year and a half.

In a Thursday morning tweet, Trump said, “Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend!”

He added: “Chill Greta, Chill!”

It's not the first time Trump has lashed out after not being recognized for his influence. In 2015, Trump attacked German Chancellor Angela Merkel for “ruining Germany” after she was named Person of the Year, when he was listed as a runner-up.

Trump is the second world leader to take aim at Thunberg this week, after her concern over the slayings of indigenous Brazilians in the Amazon drew a harsh rebuke from the Latin American nation’s president Tuesday.

“Greta said that the Indians died because they were defending the Amazon,” Jair Bolsonaro said. “It’s impressive that the press is giving space to a brat like that,” he added, using the Portuguese word ”pirralha.”

Thunberg responded by changing her bio on Twitter, where she has over 3 million followers, to say “Pirralha.”

Thunberg did not immediately respond to Trump's attack.