President Trump got into a Twitter back-and-forth with 16-year-old climate activist Greta Thunberg on Thursday over her being named Time magazine’s “Person of the Year.”

The exchange started when Trump retweeted the magazine photo of the Swedish teen and said: “So ridiculous. Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill!”

Thunberg — who has become the global face of anti-greenhouse-gas activism — fired back by updating her Twitter bio to say, “A teenager working on her anger management problem. Currently chilling and watching a good old fashioned movie with a friend.”

The official Trump War Room Twitter account later posted a version of the magazine cover with the president’s face in place of Thunberg’s.

“When it comes to keeping his promises, there’s only one Person Of The Year,” the Trump team wrote, listing the reasons he deserved the award as: “Booming Economy, Record Job Creation, Historic Tax Cuts, #AmericaFirst Trade Deals, Isis Destroyed, Building the Wall.”

Trump was on the shortlist for the prize. He was named Time’s “Person of the Year” in 2016, his inaugural year in office.

It’s not the first time Trump and the teenager have sparred on Twitter.

In September, Trump tweeted at the teenager after she gave an impassioned speech to global leaders at the United Nations, saying they had “stolen my dreams and my childhood.”

“She seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see!” Trump wrote sarcastically of Thunberg in a tweet.

Thunberg fired back by changing her Twitter bio to: “A very happy young girl looking forward to a bright and wonderful future.”