"Rocket Man is on a suicide mission for himself and for his regime," Trump said in the provocative comments.
“The United States has great strength and patience, but if it is forced to defend itself and its allies, it will have no choice but to destroy North Korea,” Trump added.
It was a forceful speech but highly unusual for the U.N.'s annual gathering of 193 member states.
In addition to using nicknames and other colloquial terms, Trump invoked his campaign rally style by boasting that "The United States has done very well since Election Day."
He also renewed hints that he would withdraw from the Iran nuclear deal, which was blessed by the U.N. Security Council and is monitored by a U.N. nuclear watchdog agency. Trump has bashed the 2015 accord since his campaign, but has so far resisted leaving.
“We cannot abide by an agreement if it provides cover for the eventual construction of a
He called it "one of the worst and most one-sided transactions the United States has ever entered into" and "an embarrassment to the United States."
“And I don’t think you’ve heard the last of it," he added. "Believe me.”
Any president's initial speech to the global body would merit attention. But Trump's has garnered even more interest because of his unpredictable nature and because he was highly critical of the U.N. during his campaign, calling it wasteful, useless and ineffective in defending democratic values.