Fortune | Dennis Jett: If you had a serious disagreement with someone, would you begin to resolve it by insulting that person and threatening to kill them? That is the approach President Donald Trump took in his debut appearance before the United Nations General Assembly on Tuesday.


In his speech, Trump referred to the North Korean dictator Kim Jong Un as �Rocket Man� and added that the U.S. was �ready, willing and able� to �totally destroy North Korea.� It would be hard to recall the last time an American president resorted to that kind of childish name-calling. The threat, however, is even more ridiculous. To say that it is hollow is an understatement.


Of course, the U.S. has the capacity to destroy North Korea. But it could not do so without provoking the destruction of South Korea and much of Japan. Kim may be a tyrant, but he is not a fool. He is not going to hand a justification for his own annihilation to Trump. While the military option is always available, it is also unthinkable. One thing such a threat will accomplish, however, is making an acceptable solution to this issue all the more difficult to find.


The references to North Korea were not the only bit of Trumpian hyperbole in the speech. The president complained about the U.S. having to bear a �disproportionate share of the burden, militarily or financially� of the UN. The U.S. contributes�22%�of the UN�s budget, which may seem like a lot until one considers that the U.S. also produces�22%�of the world�s economic output. As for the military burden, when it comes to UN�peacekeepers�in uniform, 0.06% of them are Americans�a mere 50 out of 80,067 soldiers.


Another absurdity was the assertion that wherever socialism has been adopted, it �has delivered anguish and devastation and failure.� Perhaps someone should inform the Scandinavian countries.�Studies�to determine which countries have the happiest citizens typically put them at the top of the list even though their taxes are high. Trump asked, �Are we still patriots?� One element of patriotism is caring enough about a country to pay one�s fair share of taxes. Of course, whether that take on patriotism applies to the president will never be known until his tax returns are made public.


Trump�s rhetorical excess was not limited to just the UN and specific countries, as he described his foreign policy as one of �principled realism.� Unfortunately, it contains no principles and isn�t realistic. He mentioned sovereignty 21 times, which will be interpreted abroad as the U.S. no longer caring about democracy. Exceptions to that rule are made only for countries, like Venezuela, that are included in Trump�s axis of evil. Providing sovereignty as a shield for corrupt and repressive regimes will please Russia�s Vladimir Putin, but it is not a principle of which Americans can be proud.


The policy Trump outlined is unrealistic because today the real challenges and opportunities America faces are a result of globalization. That phenomenon, by its very nature and pervasiveness, makes it impossible for a single country to meet those challenges or seize those opportunities alone. Only multilateral cooperation through organizations like the UN can accomplish that.


Perhaps Trump�s oratory hit its lowest point when he called the Iran nuclear agreement the worst deal ever and an embarrassment to the U.S. The agreement continues to curb that country�s nuclear ambitions and is far preferable to any alternative strategy. If Trump walks away from it, he will do so alone.


In a speech that was an exercise in exaggeration and bluster, Trump demonstrated that, in fact, the biggest embarrassment to this country is Trump himself.


Dennis Jett, a former career diplomat, is a professor of international affairs at Penn State University and the author of�The Iran Nuclear Deal: Bombs, Billionaires, and Bureaucrats.