President Trump called 16-year-old climate activist Greta Thunberg a "very happy young girl" who has "a bright and wonderful future."

The president tweeted his sarcastic remark late Monday night, the same day the Swedish activist delivered an impassioned speech about climate change in front of the United Nations.

"She seems like a very happy young girl looking forward to a bright and wonderful future," the president tweeted, which quote-tweeted an excerpt of Thunberg's speech. "So nice to see!"

She seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see! https://t.co/1tQG6QcVKO — Donald J. Trump (@realDonaldTrump) September 24, 2019

Trump and Thunberg went viral earlier in the day when the activist was caught glaring at the president as he arrived at the U.N. headquartersin New York City.

"You have stolen my dreams and my childhood with your empty words," she tearfully proclaimed to world leaders. "Entire ecosystems are collapsing, we are in the beginning of a mass extinction and all you can talk about is money and fairy tales of eternal economic growth. How dare you!”

Some pundits have accused environmentalists of manipulating a young girl for political purposes, including the Daily Wire's Michael Knowles, who stoked outrage by describing Thunberg as a "mentally ill Swedish child" who is being exploited by "the international Left."

Captured by @Reuters Andrew Hofstetter: @GretaThunberg watches Trump arrive at the #UNGA. Thunberg condemned world leaders for failing to take strong measures to combat climate change: ‘You have stolen my dreams’ https://t.co/e9VfOa2kwW pic.twitter.com/kbJqF4rvxc — Reuters Top News (@Reuters) September