Nic Robertson is CNN's international diplomatic editor. The opinions in this article belong to the author.

(CNN) It was a laugh that was heard around the world.

It was also a laugh that the world -- or at least its leaders -- had at the expense of President Trump.

Beginning his speech at the United Nations General Assembly this week, Trump didn't appear to expect the humorous interlude as he launched into a recital of his achievements in office to date.

There was no serious stumble, but a short pause, perhaps taking in what was happening.

Within seconds, Twitter lit up.

Not long after, television news networks -- including CNN -- were running clips of an old quote from Trump -- "They are laughing at us" -- in reference to the administration of President Obama.

The response was clear: The President screwed up. Worse, his fragile ego was under attack.

And in the words of his wife, first lady Melania Trump, the President is not to be trifled with: "As you know by now if you attack him he will punch back 10 times harder."

The world has become very familiar with the Trumpian punchback. It's been a signature of his presidency since day one.

Remember the controversy over Trump's inauguration crowds in January 2017?

He can't.

Speaking at the CIA's headquarters the day after, Trump told the gathered intelligence officials: "I made a speech. I looked out. The field was — it looked like a million, a million and a half people.''

The trouble was, pictures were placed side by side, showing the crowds at Trump's inaugurations and Obama's. They told a different story. Trump's crowd was noticeably smaller.

Trump's already raucous battle with reporters went up a notch.

His surrogate, Kelly Anne Conway, backed Trump and his spokesman Sean Spicer, saying that the White House was presenting "alternative facts."

JUST WATCHED Trump claim met with laughter by world leaders Replay More Videos ... MUST WATCH Trump claim met with laughter by world leaders 02:17

Since then, Trump hasn't let it go. He has continued to double, triple, quadruple down on his version and continued to brag of the big numbers now proven to be not "alternative facts," but a lie.

So two days after the UN appearance when Trump was asked about "LaughterGate" at a press conference, he punched back. And no one was surprised at his response: "The fake news said people laughed at President Trump. They didn't laugh at me. People had a good time with me. We were doing it together. We had a good time. They respect what I've done."

Hold on to that word, "respect." It's at the core of Trump's worldview.

His takeaway from the laughter is that he's reversed Obama's lackluster record on respect, telling reporters: "The United States is respected again. The United States was not respected. Everybody was taking advantage of us."

If the inauguration crowd discrepancy is anything to go by, Trump is going to feel the need to scratch this itch again with reporters. But for those who actually laughed at the UNGA, there may be a different cost to their irreverence of the President.

Deeper into his speech, Trump had this warning for the other 180 plus leaders: "We are taking a hard look at US foreign assistance ... Moving forward, we are only going to give foreign aid to those who respect us and frankly are our friends."

JUST WATCHED Reaction to Trump's U.N. Address Replay More Videos ... MUST WATCH Reaction to Trump's U.N. Address 04:08

Once caught in Trump's ire, world leaders find it hard to shake -- just ask Canada's Justin Trudeau and Germany's Angela Merkel.

After Trump stormed out early from the fractious G7 summit in Canada this summer, he accused Trudeau of being "dishonest," later tweeting : "PM Justin Trudeau of Canada acted so meek and mild during our @G7 meetings only to give a news conference after I left saying that, 'US Tariffs were kind of insulting' and he 'will not be pushed around.' Very dishonest & weak."

As the spat with Trudeau grew, Trump turned transactional on all Canadians: "That's going to cost a lot of money for the people of Canada."

By the time Trudeau came to New York for the UNGA three months later, Trump's grudge -- or trade negotiating tactic -- had hardened, saying he had rejected a meeting with the Canadian PM. Why? "Because his tariffs are too high, he doesn't seem to want to move and I've told him forget about it. And frankly we're thinking about just taxing cars coming in from Canada."

Those who know they laughed at Trump at the UNGA might also want to reflect on the fate of the German Chancellor Angela Merkel.

Even before he was President, Trump was giving her a hard time, criticizing the number of Mercedes Benz vehicles on the streets of New York. Months later, during her first meeting with Trump at the White House, he refused to shake her hand.

Fast-forward to this summer and Trump blasted her at the NATO summit in Belgium for falling short on military spending. At the UNGA , he tore into her for a gas pipeline from Russia. "Germany will become totally dependent on Russian energy if it does not immediately change course."

Trump's beef with Germany is chiefly about EU trade and regulations. Merkel is arguably the most influential European leader. But her two Achilles heels for criticism and isolation from the EU herd are NATO contributions and the gas pipeline.

The lesson for UN delegates who may have laughed is this: Hope you don't get found out.

President Trump likes respect. He won't forget. And he may get the last laugh.