UN Secretary-General Antonio Guterres on Monday said that US President Donald Trump's unexpected appearance at the Climate Action Summit is "a step forward".
Trump dropped in at the summit sitting through Prime Minister Narendra Modi and German Chancellor Angela Merkel's address at the event.
Guterres had a half-smile, but did not respond when asked about Trump listening at the address of the two leaders but not making an address at the summit, CNN reported.
The US President only stayed at the summit for about 15 minutes, according to journalist Jordan Fabian who has previously written for The Hill.
Trump had pulled the US out of the landmark Paris Agreement in 2017 after taking office. He has been criticised by global leaders and US Congressmen for his views on climate change.