Adopting a less confrontational stance than key allies, South Korea's president has urged the North to abandon its nuclear program and seek dialogue to prevent conflict breaking out on the divided peninsula.
Moon Jae-in on Thursday voiced support for stronger sanctions in response to the North's recent weapons tests, but his tone was in stark contrast to US President Donald Trump's dark warning at the UN General Assembly on Tuesday that North Korea would be "totally destroyed" if it attacked.
Another US ally, Japan, said Wednesday that pressure, not dialogue, was needed.
Moon cautioned that North Korean nuclear issues needed to be "managed stably" to prevent a spike in tensions and military clashes.
Pyongyang conducted its most powerful atomic test explosion and fired missiles over Japan twice in the past three weeks.
North Korea "must immediately cease making reckless choices that could lead to its own isolation and downfall and choose the path of dialogue," Moon said.
"We do not desire the collapse of North Korea. We will not seek unification by absorption or artificial means, if North Korea makes a decision even now to stand on the right side of history, we are ready to assist North Korea together with the international community," he said.
Moon was due to meet later Thursday with Trump and Japanese Prime Minister Shinzo Abe — their second three-way summit in two months — to show a common front in the pressure campaign against North Korea.
Trump said Thursday the US would impose additional sanctions over the country's nuclear buildup.
Moon urged nations to fully implement UN sanctions that were tightened against North Korea after its hydrogen bomb test on September 3.
But his remarks also exposed a potential disconnect among the allies. He said he wanted North Korea, which never reached a formal peace treaty with the South after the 1950-53 Korean War — to attend next year's Winter Olympics to be hosted by South Korea.
His government decided Thursday to resume humanitarian aid to North Korea to help children and pregnant women but didn't determine when to provide the $8 million worth of assistance.