If this question is in response to Trump's statements regarding North Korea, it is important to consider them in their fullness.
No one has shown more contempt for other nations and for the well-being of their own people than the depraved regime in North Korea. It is responsible for the starvation deaths of millions of North Koreans. And for the imprisonment, torture, killing, and oppression of countless more. We were all witness to the regime's deadly abuse when an innocent American college student, Otto Warmbier, was returned to America, only to die a few days later.
We saw it in the assassination of the dictator's brother, using banned nerve agents in an international airport. We know it kidnapped a sweet 13-year-old Japanese girl from a beach in her own country, to enslave her as a language tutor for North Korea's spies. If this is not twisted enough, now North Korea's reckless pursuit of nuclear weapons and ballistic missiles threatens the entire world with unthinkable loss of human life. It is an outrage that some nations would not only trade with such a regime, but would arm, supply, and financially support a country that imperils the world with nuclear conflict.
No nation on Earth has an interest in seeing this band of criminals arm itself with nuclear weapons and missiles. 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. 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. That's what the United Nations is all about. That's what the United Nations is for. Let's see how they do.
~Donald Trump, speech before the United Nations
What may be seen as an threat is instead a diplomatic ultimatum, given in response to the threat of war and provocation being proffered by Kim Jong-Un. This would be in keeping with the preamble can be leveraged against the actions taken by North Korea against their populace.
However, there isn't much teeth the UN can implement against these perceived threats. Just look back to the numerous votes that have been held against Israel.
Even closer to the matter, consider North Korea itself; Kim Jong-Un has threatened to destroy South Korea, has made claims NK could destroy the US, and specifically threatened New York.enter link description here.
In response to these and previous events, the UN Security Council has increased sanctions against North Korea, China has admitted they won't back North Korea if that country attacks first, and warned North Korea against being provocative on August 5th. Between the 5th of August and September 15th, same year, North Korea launched 5 missiles, the last two of which had flight paths over Japan. The response was talk of more sanctions, and starting the calls for political force by other means, i.e. military might.