One minute he’s threatening nuclear war via tweet; the next his adoring followers are chanting "Nobel, Nobel!" at one of his ubiquitous, campaign-style rallies. It’s hard to keep up with President Trump’s North Korea policy, such as it is.

First thing’s first: though I’ve been a regular critic of this administration, I fully support the planned talks between Trump and Kim Jong Un. As an American, and a (mostly) rational human being concerned about the end of the world, I’m rooting for peace and could care less whether its a Democrat or Republican president who achieves it. There’s little room for politics in such existential situations, or, at least, there should be. Besides, we’ve never really tried a one-on-one summit and the more "standard" policies of past presidents have utterly failed.

But what happens if the talks fall apart, or don’t happen at all? How will President Trump respond to such a staggering blow to his ego – should the deal-maker fail to close this big time deal? In a recent interview, former Chairman of the Joint Chiefs of Staff, Mike Mullen, expressed his deep fear that the chances of war will increase dramatically if the summit falls apart. After all, what options would be left on the table? President Trump has already escalated to the brink of war with his threats of unleashing "fire and fury," and pressing his "very big" nuclear "button." If the talks break down – as they are likely to do – will the cabinet Warhawks such as National Security Adviser John Bolton and Secretary of State Mike Pompeo push for a preventive strike or outright war? I wish the answer was a definitive no; but it’s not.

War with North Korea should be the ultimate non-option, a course to be avoided at all costs and only pursued in the case of an (unlikely) blatant North Korea invasion of the South. There are two main reasons for avoiding the cataclysm of war. First off, it is unnecessary and undesired by all the key players involved. Second, it would be a veritable catastrophe.

South Korea has the most to lose (besides the North) in any preventive war. And there is little enthusiasm for war among South Korea’s populace or its senior leaders. In fact, the recent thaw in the North-South relationship has been a bottom up, indigenous phenomenon, pursued by Korean leaders on both sides of the demilitarized zone (DMZ). Whether the rapprochement endures remains an open question, but South Korea seems genuinely committed to easing tensions and pursuing diplomacy with the North. Indeed, all the hawkish talk and threats from Trump and his team has been far too bellicose and out of sync with that of our South Korean allies. This is odd, given that is the South which faces the more existential threat from the Kim Jong UN regime. We should take our cues from them – its their country.

Second, a war with North Korea would be a military and humanitarian catastrophe for which the U.S. military may be grossly unprepared. Don’t take my word for it. In December 2017, NATO Secretary General Jens Stoltenberg stated that "war in that region would be catastrophic and it would have global consequences." A few months earlier, Trump’s own Secretary of Defense, James Mattis, also described such a war as "catastrophic," and recommended leading with diplomacy, not military options.

Senior military and political figures have also intimated that any war would quickly escalate and that a "limited" conflict is unlikely. The current Chairman of the Joint Chiefs, General Joseph Dunford, wrote a letter which informed Congress that in the event of war a ground invasion would be necessary to locate and neutralize North Korean nuclear sites. Furthermore, former deputy commander of US Forces Korea, Lieutenant General Jan-Mare Jouas, sent another letter warning that war would result in "an enormous casualty and refugee crisis."

So what would that war look like? In short: hell. According to a Congressional Research Service report, up to 300,000 people could perish in the first few days of fighting – something the world hasn’t witnessed since the end of World War II. North Korea has a substantial chemical, biological, and nuclear weapons capacity, and might just use one or all of these tools if it feels cornered or in danger of regime change.

On the conventional side, the North has nearly 8 million troops between its active, reserve, and paramilitary forces, all of whom have been indoctrinated since birth to believe the US is an existential enemy. Kim Jong UN also has an estimated 10,000 artillery pieces dug into the slopes north of the DMZ. Within seconds of the outbreak of war, these guns could drop high explosives on the capitol city of Seoul, and endanger that lives of the some 25 million South Koreans who live within range of the North’s artillery. Furthermore, imagine the refugee crisis as the those civilians inevitably flee south.

Most military experts agree that the North would ultimately lose such a war. South Korea has a substantial, modern military force of its own, and powerful allies among NATO members and the US But that doesn’t mean it’d be easy. After causing hundreds of thousands of deaths in its first few days, such a war is unlikely to end once Kim’s army is beaten. Experts note that the postwar occupation would be lengthy and that North Koreans would be unlikely to passively concede defeat. It is far more likely that the situation would deteriorate into the sort of quagmire of insurgency to which the US has grown accustomed in the Middle East.

War would, as we’ve seen, be a nightmare and perhaps see the bloodiest combat since the Second World War. It would endanger the 28,000 US troops already in South Korea (and their families and other civilian expatriates) but would also require a quick, massive intervention of American reinforcements. That’s where it gets tricky, because, well, where are those necessary troops going to come from? The US military is already overstretched and exhausted after 17 years of war. The relatively modest manpower of this all-volunteer force is still currently engaged in hot wars in Syria, Iraq, Afghanistan, Libya, Pakistan, Yemen, and West Africa. It’s also busy containing Russian "aggression" in Eastern Europe and balancing against China’s growing power in South East Asia. A lengthy, bloody crusade on the Korean Peninsula just might "break" the active duty force and require a substantial commitment of the National Guard and Reserves. Are Americans really prepared for that level of engagement?

The sad truth is that the people of this country are unlikely have much say at all. In the 21st century, the United States possesses a peculiar system for war-making, whereby a single executive – Mr. Donald Trump – has the sole authority to start an outright (and potentially nuclear) war. Congress and the people have ceded their constitutionally mandated role as arbiters of war and peace, and handed full control of the war machine to an increasingly imperial presidency. This is not, by the way, a function of Trump, but rather an ongoing process developing incrementally for some 70 years.

The Korean Peninsula remains, each day, locked and loaded and on the precipice of cataclysmic war. This is why we must all root for the success of Trump’s, or any president’s, diplomatic outreach. But, if talking fails, shooting might just commence. That is the ultimate non-option for humanitarians and strategists alike, and to be avoided at all costs.

Which leads us to a discomfiting question: are we willing to bet millions of lives that (notoriously thin-skinned) President Trump and company realize this and won’t overreact should the planned talks fail?

That’s a big if.

Danny Sjursen is a US Army officer and regular contributor to Antiwar.com. He served combat tours with reconnaissance units in Iraq and Afghanistan and later taught history at his alma mater, West Point. He is the author of a memoir and critical analysis of the Iraq War, Ghostriders of Baghdad: Soldiers, Civilians, and the Myth of the Surge. Follow him on Twitter at @SkepticalVet.

[Note: The views expressed in this article are those of the author, expressed in an unofficial capacity, and do not reflect the official policy or position of the Department of the Army, Department of Defense, or the U.S. government.]

Copyright 2018 Danny Sjursen