After telling world leaders at the UN climate change summit they had stolen her childhood with "empty words", the Swedish activist then stared daggers at US President Donald Trump.
Climate activist Greta Thunberg may just be 16, but she is making a name for herself for calling out world leaders for their alleged inaction on climate change.
But when she spotted Donald Trump at the UN Climate Summit on Monday, it wasn't her words that caught the public's attention - it was her glare.
Watch the 16-year-old's reaction to the appearance of Trump in the player above.
As the US President, who has stated he doesn't know if humans have caused climate change despite the overwhelming scientific consensus, made his way into the room, Thunberg appeared to glare angrily towards him.
Earlier she had made an impassioned speech at the summit, admonishing world leaders for their "empty words", and accusing them of being only concerned with "money" and "fairy tales of eternal economic growth".
Donald Trump took to Twitter to apparently mock the teenager, saying she "seems like a very happy young girl".
Greta Thunberg inspired an ongoing wave of school strikes to pressure politicians to act on the threat of man-made climate change - a movement that has inspired and made activists of millions of youngsters around the world.