New York, New York - President Donald Trump relentlessly mocked the United Nations on Tuesday in his first address since his White House comeback, blasting it for failing to bring peace and claiming the world body encourages illegal migration.

In his return to the UN General Assembly podium, Trump accused the UN of fostering an "assault" through migration on Western countries that he said were "going to hell."

He likewise used the major forum to denounce efforts to reduce global warming, calling climate change concerns "the greatest con job ever perpetrated on the world."

"What is the purpose of the United Nations?" asked Trump.

"All they seem to do is write a really strongly worded letter," he said. "It's empty words, and empty words don't solve war"

The 79-year-old even complained about a broken escalator and teleprompter at the New York headquarters of the UN, which he has repeatedly targeted during both of his presidential terms.

"This is these are the two things I got from the United Nations, a bad escalator and a bad teleprompter," he said.

Touting what he said were his efforts to end seven wars, Trump turned to two where his outreach has produced no results – Russia's invasion of Ukraine and Israel's war on Gaza following Hamas's October 7, 2023 attack.

He called recognition by a slate of Washington's allies of a Palestinian state a "reward" to armed group Hamas for "horrible atrocities" and urged the group to release hostages to reach peace.

Trump lashed out at European allies, as well as China and India, for failing to stop oil purchases from Russia, while remaining relatively restrained on Moscow even as he said Washington was ready to impose unspecified sanctions.

Some of his strongest language was reserved for migration as he lambasted the UN for "funding an assault" on Western nations.

"It's time to end the failed experiment of open borders," Trump said. "Your countries are going to hell," he said, also attacking London's Mayor Sadiq Khan, the first Muslim mayor of a Western capital.