The annual summit brings together thousands of world leaders, diplomats and advocates. And a lot of world leaders have been waiting to see what he meant by that. He also took aim at arguably the largest thorn in his side: Kim Jong-un's regime in North Korea.
Pyongyang has launched dozens of missiles as it accelerates a weapons program created to provide the ability to target the United States with a powerful, nuclear-tipped missile.
Unless North Korea backs down, he said, "We will have no choice than to totally destroy North Korea".
If diplomacy fails, she says Defense Secretary Jim Mattis "will take care of it". Specifically, he came to the defense of the sovereignty of Ukraine and the South China Sea - that is, in the face of challenges from Russian Federation and China.
The United States has slapped several rounds of sanctions on the South American country after Venezuela held elections in late July for the National Constituent Assembly tasked to rewrite the constitution.
Mr Trump's 40-minute speech, which was met by restrained applause in the chamber, also set out some broader principles of U.S. foreign policy as Mr Trump espoused the notion of national sovereignty, a common theme of his presidential campaign.
Turning to Iran, Trump called the 2015 nuclear deal negotiated by his predecessor, Barack Obama, was an embarrassment and hinted that he may not recertify the agreement when it comes up for a mid-October deadline. He did warn today, though, that you haven't heard the last about that.
US president Donald Trump delivers remarks to military personnel and families at Joint Base Andrews Maryland, US, September 15, 2017.
"The United Nations was founded on truly noble goals".
Trump will also argue that his nationalist doctrine of "America First" is not an impediment to worldwide cooperation, but rather a rational basis for countries to work together, without losing sight of their own self-interest. How did he address that?
"To honor the people of our nations, we must ensure that no one and no member state shoulders a disproportionate share of the burden", Trump said at a UN event on reform. That's what the United Nations is for.
HORSLEY: This was a full-throated defense of sovereignty.