Kim Jong Un may be on a suicide mission, as President Donald Trump told the U.N. General Assembly on Tuesday, but nobody in the White House with a serious understanding of the effect of war with North Korea would approve of a U.S. response that would indulge it, experts say.

Tens of thousands of civilians would likely die in the first hours of a resumption of the Korean War, if only due to the conventional rockets Pyongyang has hidden in the mountains along the Demilitarized Zone and aimed at Seoul. That estimate does not include the 30,000 U.S. forces based on or near the border and the 200,000 American expatriates living in the capital city.

The number also does not account for North Korea's ability to employ nuclear weapons, whichcould put the overall death toll as high as millions.

And yet, in the most prominent international address of his presidency, Trump on Tuesday escalated the U.S. military threat against Kim's regime.

"If it is forced to defend itself or its allies," Trump said of the U.S., "we will have no choice but to totally destroy North Korea."

The purpose then of Trump's bellicose rhetoric is largely to present military action as what diplomats call a "credible threat," forcing all sides to opt instead for peaceable negotiation. It's a familiar tactic for North Korea, as most experts agree that's what inspired Kim to pursue nuclear weapons in the first place.

"Both sides are fully aware that open hostilities between the U.S. and North Korea would result in catastrophe," says Charles Armstrong, a