North Korean leader Kim Jong Un's habit of ignoring the demands of President Donald Trump and the international community is a characteristic of his millennial generation, the author of a new book on the rogue regime said.

Donald Trump to Kim Jong Un: My Nuclear Button Is ‘Bigger And More Powerful’

Kim, who apparently was born in the early 1980s, is "ignoring them and ignoring them in a way that's making fun of them," Loretta Napoleoni, author of North Korea: The Country We Love to Hate published earlier this year, told Newsweek. "This is so millennial."

Besides defying a slew of United Nations sanctions by continuing to develop Pyongyang's missile development program, Kim has fired verbal threats at Trump that are unlike those uttered by world leaders who were involved in prior nuclear conflicts.

Related: North Korea could become leading supplier of crystal meth, fake bitcoin following sanctions, expert warns

"It was all very heavy and emotional almost," Napoleoni said, "and here it's actually more like a joke."

Napoleoni, an economist who started following North Korea in the 1980s, offered as an example Kim's statement in his New Year's address that "the U.S. should know that the button for nuclear weapons is on my table."

"The nuclear button is sitting in front of me, and I can press it at any time. I don't think it's emotional at all. I think it's very much pragmatic," the author said. "It's not the language that plays on emotions of people—it's more of language that tends to ridicule the adversary."

In her book, Napoleoni detailed other aspects of Kim's leadership that are millennial in style.

"Kim Jong-un, the millennial, has accelerated the nuclear program, investing in it heavily and dismissing as a deterrent the regular army, which he considers weak and somehow obsolete," she wrote. "The verbal confrontations with Donald Trump, Shinzo Abe and the South Koreans are pure propaganda. Kim Jong-un has no intention of bombing anybody, but he does want to prove that he could."

Napoleoni also drew a parallel between Kim and another millennial leader, Saudi Arabian Crown Prince Mohammed bin Salman. Both men "have purged the old guard and present themselves as anti-corruption leaders," she stated in her book.

"Both countries are set to be ruled for decades to come by young millennial leaders who are very much the product of the authoritarian and brutal regimes they were born into," Napoleoni wrote. "The sooner we realize this, the sooner we can begin working toward a new world order."