Tens of thousands of North Koreans gathered for a rally at Kim Il Sung Square in Pyongyang, North Korea, in August 2017 after the United Nations announced a new round of sanctions. (Jon Chol Jin/Associated Press)

When President Trump boasted that he had a “bigger” nuclear button than North Korean dictator Kim Jong Un, members of both parties rightly condemned his reckless bravado about possible nuclear war with North Korea. The fear most expressed was that Trump will induce Pyongyang to miscalculate and launch its own strike or that we will, as we’ve already done, freak out our allies so much that they will pursue unsatisfactory side deals. Less discussed, however, has been the impact that Trump’s nonchalant threats of nuclear war have on U.S. policy planners, Congress and the public. The American president, for the first time since 1945, is making nuclear war an acceptable policy option. Moreover, in concert with his overheated national security team, he is normalizing the idea of any kind of military solution to North Korea’s development of nuclear weapons.

A military option is quite simply not an option, and both the Trump administration and Congress should stop pretending that it is. To the contrary, Congress and responsible voices outside the administration need to make clear just how unacceptable and devastating war would be.

In November, in response to an inquiry from two Democratic congressmen, the Pentagon made clear that the only way to ensure military success would be a ground invasion of North Korea. The Pentagon stated that “the only way ‘to locate and destroy — with complete certainty — all components of North Korea’s nuclear program’ is through a ground invasion. . . . We assess North Korea may consider the use of biological weapons as an option.” The parameters of such an invasion and the potential casualties are classified, but in non-classified settings, others have made good-faith assessments of the toll that a land war in North Korea would take.

In April 2017, one analyst warned:

Should Pyongyang live up to its threat of turning Seoul into a “sea of fire,” casualties in the larger Seoul metropolitan area alone may surpass 100,000 within 48 hours, according to some estimates, even without the use of North Korean weapons of mass destruction. The U.S. Department of Defense assessed that a Second Korean War could produce 200,000-300,000 South Korean and U.S. military casualties within the first 90 days, in addition to hundreds of thousands of civilian deaths.

That could far outpace U.S. casualties in all wars since World War II.

Congress has looked at this as well, although with far less urgency and public debate than are warranted under the circumstances. The Congressional Research Service last year undertook its own study, finding:

Under current U.S./ROK [Republic of Korea] operational plans (OPLANS), the South Korean government has publicly stated that the United States would deploy units to reinforce the ROK in the event of military hostilities. In the event of wartime, and depending on those circumstances, official ROK sources note that up to 690,000 additional U.S. forces could be called upon to reinforce U.S./ROK positions, along with 160 naval vessels and 2,000 aircraft.

That in and of itself raises the question as to whether we have a military of sufficient size (we don’t) to fight such a war while maintaining sufficient strength to handle other threats (e.g. in the Middle East, in the South China Sea).

The response from North Korea could be devastating:

The Kim regime could respond to any kind of U.S./ROK military activity through a variety of conventional and unconventional means, any use of which could escalate into a full-scale war on the Korean Peninsula. Detailing specific possible responses is difficult, however, given the scarcity of relevant available literature. In the first instance, despite noted deficiencies in its overall conventional force structure, many observers expect the DPRK would employ its conventional artillery toward targets in South Korea and inflict considerable damage upon Seoul (as detailed in the next section).

In terms of unconventional responses, the DPRK might employ its highly trained SOF to sabotage U.S./ROK targets south of the DMZ. The DPRK [North Korea]  might also employ weapons of mass destruction during a conflict with the U.S./ROK. A possibility also exists that a conflict with DPRK could escalate into nuclear warfare, the result of which could be radioactive contamination that could affect all states in the immediate region, including China, Japan, and South Korea. As a consequence in this possible contingency, U.S. forces would likely be required to operate in WMD-contaminated zones, and the Korean Peninsula itself could face enormous devastation and loss of life. North Korea also could launch a cyberattack against the United States, South Korea, or other targets. Further, some observers contend that North Korea may already have the capability to launch a nuclear attack against the continental United States, possibly delivered covertly by smuggling, or even through using container ships as a means of delivery.

The scope of such a conflict would be beyond anything we have seen in the lives of most Americans. The Congressional Research Service finds that “an escalation of a military conflict on the peninsula could affect upwards of 25 million people on either side of the border, including at least 100,000 U.S. citizens (some estimates range as high as 500,000). Even if the DPRK uses only its conventional munitions (which most analysts believe would be unlikely given North Korea’s arsenal of WMD capabilities), some estimates range from between 30,000 and 300,000 dead in the first days of fighting, given that DPRK artillery is thought by some to be capable of firing 10,000 rounds per minute at Seoul.”

That’s not the only horrendous ramification of war. Other consequences of a full-scale war would include a North Korean missile attack on Japan (“the greater Tokyo area alone has a population of about 38 million”) and devastation of South Korea’s economy (“a conventional war could amount to 60%-70% of South Korea’s annual GDP, which in 2016 was $1.4 trillion … [and] if North Korea detonated a 10 [kiloton] nuclear weapon in Seoul, the financial costs would be more than 10% of South Korea’s GDP over the ensuing 10 years”). It is unrealistic to think that American taxpayers would not bear a substantial amount of the burden of rebuilding. Even if China did not join the hostilities, we would not doubt face a “major rupture” with China, “which is the United States’ top trading partner and holds upwards of $1.15 trillion in U.S. bonds as of June 2017.” China might also choose to act opportunistically during hostilities or establish itself as the premier power in the region in the wake of a devastating war. And lastly, given Russia’s increasingly aggressive posture, the United States would have to consider the risk that during such a war Russia would move militarily against one or more of the Baltic states.

Even a cursory look at the contours of another Korean War should be enough to demand that Trump tamp down on casual suggestions of nuclear war. The larger question, however, is why among the “grown-ups” in the administration a military solution is apparently being seriously considered. It’s time for congressional hearings and a much more robust and serious discussion about the military option. Trump’s threats are reckless, but the policy that the threats suggest is inconceivable.