In case of war with North Korea, the US would face a military challenge as perhaps never before in the last seventy years. This is why a conventional deterrence is actually more important than the nuclear one if we break down a realistic war scenario. The downside is that the DPRK is fully aware that if it responded to a US attack, even in a limited way and only on military targets, it would be flagged as an aggressor, paving the way for a larger foreign intervention.
To answer this question, it is necessary to examine what would entail a US attack on North Korea. Suffice it to say that as the neocon Senator John McCain has admitted, the US would be unable to defend Seoul (as well as its US bases nearby) in the first 24 to 48 hours of a conflict. A city of 20 million inhabitants, together with military bases containing thousands of soldiers, would suffer untold loss of life.
The United States would certainly suffer huge losses, revealing weaknesses that could be exploited in future conflicts, a consideration that would need to be considered if contemplating shooting down DPRK missiles.
China would certainly not be happy to risk a humanitarian catastrophe on its own border, not to mention being eventually forced to intervene to defend its ally (there is a treaty between the two countries). Japan and South Korea would be hit hard, being clearly exposed to a North Korean retaliatory attack; so they clearly do not want a war with Pyongyang. The great truth about the Korean Peninsula is that despite the fact that every country flexes its muscles and seems ready to act, no one wants this eventuality, as no one could win this war, and everyone would suffer devastating effects both economically and militarily. This is not to mention the popular uproar that would arise from so many civilian deaths, let alone were there to be a nuclear escalation.
In the Korean peninsula, we are faced with a great strategic game in which the DPRK becomes more difficult to attack with each passing day, thanks to its conventional forces rather than its nuclear power. This is something that western planners tend to ignore in order to avoid accentuating the power of the DPRK. Unfortunately for them, this is something that is far too well known to US soldiers, and especially South Koreans, which is why a real attack on the DPRK is absolutely out of the question for Seoul.
Finally, there is a worrying aspect to consider for the DPRK’s opponents, namely the alleged ways in which the DPRK preserves and launches its conventional forces. In the parade on April 15, a large availability of solid-fuel mobile platforms was displayed. This creates two great advantages: the first being the ability to launch a missile within a short space of time, thereby minimizing the risk of detection during such things as refueling operations; and the second, of course, being the ability to launch a missile and then quickly change position (shoot and scoot). With mobile launchers, it is impossible to track and hit all such systems in a preemptive attack. This is without factoring into the equation the North Korean submarines that are said to be able to launch medium- and short-range SLBMs with conventional or nuclear warheads.
An indication of the confusion that prevails amongst military planners regarding North Korea can easily be seen with the story of USS Carl Vinson. Ships with significant attack capabilities, Trump said a few days ago, were sailing towards the DPRK with the intention of inducing Kim to talks through military intimidation. However, the reality was that the carrier group was actually thousands of miles away, continuing to navigate in the opposite direction. Even without this ridiculous situation, US military leverage hardly works with the DPRK for the reasons explained above.
With this unprecedented gaffe, the United States is at least divided internally on what to do, sending a troublesome message to its allies, leaving them with the following set of questions: Is Trump really in control of the armed forces? Can his words be taken seriously? Is he consistent with his intentions? The first 100 days of the Trump presidency raise these questions, and in difficult scenarios such as the one that obtains in the Korean Peninsula, they take a heavy toll. At the end of the day, in Korea we are faced with a lot of smoke and mirrors, threats and promises. But realistically, no one wants a conflict.
On the contrary, war rhetoric rewards virtually all the actors involved.
Japan and South Korea aim for more American involvement in the region, but for very different reasons. The South Korean elite is in a crisis, Park Geun-hye daughter of the founder of the country having been fined for corruption and the likely new president seeming to have positions on the DPRK and the alliance with the US that are very different from that of his predecessors. The danger the US sees is that a substantial part of the South Korean elite prefers a shift from a strongly anti-DPRK and pro-US policy to a more balanced one, especially with China, South Korea's main partner. The best solution to prevent this change is to raise the level of tension with the DPRK (and, as a consequence, with China), aiming to solidify the US presence in the country (witness the urgent deployment of the THAAD system, which candidate Moon Jae-in seems to oppose).
The Japanese case is even more explicit, with Abe's nationalist vision aiming for a constitutional revision that does away with the limits placed on Tokyo’s armed forces. The US war industry will of course benefit, ready to sell weapons of all kinds to Japan in to reassure its ally over the “North Korean threat”. China and Russia start from different assumptions in their relations with the DPRK, but both have enough problems on the world stage to become embroiled in an open crisis involving the DPRK. Obviously, Moscow and Beijing would like a reasonable diplomatic resolution, negotiated by several actors, with the backdrop of talks with the Iranian Islamic Republic over nuclear matters.
The latter is a matter, as we have seen, that is difficult to reach between Washington and Pyongyang for lack of mutual trust. In the case of an extended negotiation with other regional and global actors, perhaps Beijing and Moscow could ensure the inviolability of the DPRK’s territory in exchange for disarmament that would lead to a lifting of the sanctions and embargo on Pyongyang.
This is still a controversial consideration, as Russia and China should provide military aid to the DPRK without Pyongyang having nuclear deterrence. From another point of view, it is the conventional forces of the DPRK that provide real deterrence, so a multi-stakeholder peace proposal is to be considered the second most likely outcome of tensions in the region.
What will happen next?
In the first place, a likely outcome is immobility and inaction, coupled with strong statements filled with threats from both the US and its allies, as well as a defiant response from Pyongyang. Personally, I am convinced that Kim would like an acknowledgement of his country’s status as a nuclear power in exchange for a halt in his development of nuclear weapons, thereby standardizing relations with neighbors and with the United States as well as gaining greater independence from China.
It should not be surprising that Pyongyang also has a more multi-polar vision in its foreign policy, but this relies more on Washington than Beijing. Unfortunately, it is difficult to imagine an immediate resolution of the situation given the commitment of Japan and South Korea to maintaining a hostile climate for the DPRK in the region, calling for American involvement. It is likely that the situation will not degenerate but instead return to normal as tensions in the region progressively subside, without seeing any particular concessions from either side.