Donald Trump has said America would "totally destroy" North Korea if it is attacked by Kim Jong-un's regime.
The President of the United States made the pledge in his first address to the UN General Assembly, which also focused on international terrorism, migration and Iran.
"The United States has great strength and patience but if it is forced to defend itself or its allies we will have no choice but to totally destroy North Korea," Trump said.
"Rocket man is on a suicide mission for himself and for his regime. The United States is ready, willing and able but hopefully this will not be necessary."
He also criticised nations that trade with North Korea, and those supplying it with weapons.
Following a hydrogen bomb test by North Korea earlier this month, the UN has enforced further sanctions on the country.
The UN Security Council has also banned textile exports from North Korea, and has capped crude oil imports.
However, Jong-un has promised to complete his country's nuclear programme, and has said he will build a military force to rival America's.
Iran nuclear deal
Trump also suggested in his speech today that he might scrap the deal the US struck with Iran over its nuclear capabilities.
"That deal is an embarrassment for the United States and frankly I do not think you have seen the last of it," Trump said.