For a week devoted to diplomacy, the language Trump and his counterparts employed in New York was anything but diplomatic. By the time Trump departed late Thursday for his golf resort in New Jersey, the leaders of both North Korea and Iran had thumbed their noses at Trump's bombast, responding with their own insults.
In some ways, the outsized response was a reaction to Trump himself, who did not attempt to dim his bluster at this week's proceedings at the UN. In his maiden address to the General Assembly, Trump mocked North Korea's young leader Kim Jong Un as a "rocket man" and threatened to destroy his entire country.
Kim's foreign minister, who is attending the UN meetings in New York, went further, telling reporters that North Korea may dramatically increase frictions by testing a hydrogen bomb above or on the surface of the Pacific ocean.
Meanwhile, Trump's declaration that the Iran nuclear deal amounts to an embarrassment for Americans drew an angry rebuttal from Hassan Rouhani, the moderate Iranian President who helped broker the agreement during the Obama administration.
"It will be a great pity if this agreement were to be destroyed by rogue newcomers to the world of politics," Rouhani said during his own UN address.
And like Kim, Rouhani only vowed to continue taking the type of provocative action that has prompted angry rebukes from Washington.
"We will promote our defensive and military power as much as we deem necessary," Rouhani said during a parade to mark 36th anniversary of the start of the Iran-Iraq war. "We seek no one's permission to defend our land."
The furious replies from two US foes suggest a level of personal brinkmanship that previous presidents have sought to avoid. Unlike Presidents Barack Obama or George W. Bush, Trump has lobbed his own signature barbs toward the stickiest foreign policy crises.
"I think the challenge for President Trump is to avoid saying things that causes him to be seen as part of the problem," said Gary Samore, a top Obama administration nuclear adviser. "Many governments are alarmed at the escalation in rhetoric. And it would be in the interests of the United States for President Trump to appear to be reasonable and very responsible and let the North Koreans engage in wild rhetoric and personal insults."
"Unfortunately, I think the President's in danger of being in a situation where he's seen at the same level as Kim Jong Un in terms of irresponsible words," said Samore, now at Harvard University's Belfer Center for Science and International Affairs.
On Twitter Friday, Trump did not seek to cool matters.
"Kim Jong Un of North Korea, who is obviously a madman who doesn't mind starving or killing his people, will be tested like never before!" he wrote.
That was a harsher line than Trump adopted within the hushed confines of the Palace Hotel on Thursday as he darted from meeting to meeting with Asian leaders, who fear the heightened rhetoric could result in war.
Seated alongside South Korean President Moon Jae-in and Japanese Prime Minister Shinzo Abe, Trump appeared open to talks with Kim, asking "why not" when asked by a reporter whether dialogue was still possible with Pyongyang.
And he demonstrated a continued commitment to economic efforts
meant to choke off support for North Korea, announcing harsh sanctions on foreign banks and individuals who do business there.
The measured language contrasted with his general assembly address, which threatened annihilation if the threats from North Korea continued
. Kim's statement -- which he was seen, but not heard, reading from wood-paneled office -- was the first time a North Korean leader had directly addressed a foreign counterpart
, furthering the impression the two men are locked in a battle of personalities.
"He made unprecedented rude nonsense one has never heard from any of his predecessors," read Kim's statement, which was read by a presenter on the state-run news agency. "A frightened dog barks louder."
The remarks impugned Trump as "hard of hearing" and, implied by the use of "dotard," elderly -- both deeply personal rebukes that strike at Trump's sensitivities.
"Word and talk is cheap," Trump's counselor Kellyanne Conway said on Fox News Friday, adding that Trump is more interested in assessing Kim's actions. "For this non-politician who is accustomed to dealing with product and deliverables in action, you see the world responding."