Trump not only disgraced himself and America in his speech to the United Nations, but he just recklessly escalated tensions with a casual threat to "totally destroy" North Korea.

In what might be his most unpresidential moment yet, Donald Trump threatened to “totally destroy” North Korea while addressing the United Nations.

It was not a carefully planned part of his speech, vetted by Secretary of State Rex Tillerson, United Nations Ambassador Nikki Haley, or any of his aides. Instead, it was a typical Trumpian moment in which he added, at the last minute, a threat of war, the consequences of which he clearly does not understand. According to MSNBC reporter Kristen Welker, Trump added those words himself.

“The United States has great strength and patience,” Trump said. “But if it is forced to defend itself or its allies, we will have no choice but to totally destroy North Korea.”

New York Times reporter Peter Baker noted in a White House pool report that the audience of world leaders sat “stone faced,” watching Trump, though there was a “buzz in the room” when Trump made his casual threat and called North Korea leader Kim Jong Un “Rocket Man on a suicide mission” — another embarrassing and childish line Trump repeated from his bizarre Tweet over the weekend, which was added at the last minute:

Despite Trump’s bluster about North Korea, the reality is that nuclear war against the country, which shares a border with our close ally, would be catastrophic.

In 1994, when President Bill Clinton contemplated the use of force to knock out the North’s nuclear weapons program, the then commander of U.S.-Republic of Korea forces, Gary Luck, told his commander in chief that a war on the peninsula would likely result in 1 million dead, and nearly $1 trillion of economic damage.

Three decades later, the damage would almost certainly be worse. But that is not something Trump appears to understand. He had made numerous comments about nuclear weapons, before and after the election, all of which reveal a terrifying ignorance about them.

In August 2016, he reportedly asked a foreign policy expert, “If we have them, why can’t we use them?”

Last December, he called for the United States to “strengthen and expand its nuclear capability.” He then followed up that astonishing declaration by telling “Morning Joe” co-host Mika Brzezinski, “Let it be an arms race. We will outmatch them at every pass.”

Now, as president, Trump has issued a threat against North Korea that all but dares the nation to further provoke the United States. If Trump were to follow through with his threat against “Rocket Man,” it would lead to unspeakable devastation for millions of innocent people.

It’s the kind of reckless threat that the president of the United States should never make. But Trump has already proved, in his brief time in office, that he doesn’t care at all about what a president should do — regardless of the consequences for America’s safety and security around the world.