Would defense based only on nuclear weapons work? [closed]

Question

There's an article in the Japanese constitution forbidding the country from going to war. The country nonetheless maintains a substantial self-defence force.

I'm wondering if Japan can feasibly disband the self-defence force and rely only on nuclear deterrence. The idea is that since they will only have nuclear weapons, they would not be able to intervene internationally in limited fashion. In other words, this would effectively force the country to adhere to its constitution. From another angle, doing this also means that if another country attacks them, they can only retaliate with nuclear weapons - there is no chance that they "react proportionally" in a conventional war, and therefore attacking them might be too costly. There's also an advantage in cost: the self-defence force currently has a budget of ~US$50 billion per year, while the UK's Trident program (which is the UK's nuclear deterrent) only costs ~£2 billion per year.

Doing this would involve developing nuclear weapons, but Japan is a nuclear latent state so this should be straightforward.

Is this feasible? If so, has it been suggested? If not, why not?

Answer 1

From another angle, doing this also means that if another country attacks them, they can only retaliate with nuclear weapons - there is no chance that they "react proportionally" in a conventional war, and therefore attacking them might be too costly.

But that goes both ways, would the defending country resort to a nuclear strike in response to a small attack or in case of a small war? The answer is no, because such a disproportionate response would be an act of extreme aggression. That would make the defending country which has launched nuclear weapons the aggressor (the first to escalate to a nuclear war).

Potential attackers can abuse that reluctance of the defending country to go nuclear by employing salami tactics. Such hesitation is illustrated by this Yes, Prime Minister clip in which the fictional UK Prime Minister is asked when he should launch nuclear missiles in response to a potential Russian invasion of Western Europe. Salami tactics refers to taking small slices in a broader conflict. Individual slices would be chosen by the attacker to get ahead in a broader offensive without provoking an unwanted response (sanctions, a military response, a nuclear response).

A practical example of such a conflict takes place in the South China Sea. Through different tactics (diplomatic, economic, militarily), China is able to strengthen its position in the South China Sea. None of the individual actions warrant a military response, but combined they are enough for European and American navy ships to patrol the area. That's using expensive military equipment (navies) as a deterrent.

If you only had nuclear weapons then you'd be nowhere. You could fire them in the South China Sea, but that won't achieve anything positive. And firing them at China would start a nuclear war. So without a conventional military, you'd be unable to stop such intrusions.

Of course, in this example there's a united effort to keep the South China Sea accessible as the international waters they are. While it's a local issue, it affects the international community because many shipping routes pass through there. When there's only a local issue, then you cannot rely on the international community coming through to defend you.

Even if you have an understanding with a superpower to defend you, which Japan has with the US, it's always a dependent relationship. For example, the superpower can try to renegotiate the understanding when it feels like it, as the US did in 2019.

I should say that such alliances aren't uncommon for very small countries. Wikipedia has a list of countries without armed forces. Many of these countries are under the protection of a larger neighbor.

In conclusion, nuclear powers without a conventional military lack the versatility to engage in regular conflicts. That means such a defense strategy would have to rely on alliances.

Answer 2

No, it wouldn't, and the reasons are the following:

First, that would only work if the opponents believed that the nation that had the nuclear weapons would be willing and able to use them. So, minor provocations that were below the "threshold" of what a reasonable country would be willing to use nuclear weapons for would not be deterred by their nuclear arsenal. Also, immediate neighbors might suspect that they'd be unable to launch an attack without risking "blowback" on themselves or their allies.

Secondly, you need to consider how such a country would defend itself from other nuclear countries. As I said above, nuclear weapons are only a deterrent if the other side believes that you're willing and able to use them. If you used a nuclear weapon against another nuclear state (or another country that was closely affiliated with a country that had them), they'd presumably simply retaliate with their own nuclear weapon strike.

In fact, if they believed that the country in question was about to launch a nuclear attack, they could simply launch their own preemptive nuclear strike in an effort to incapacitate them. (This is especially the case given that the country's only offensive weapon is nuclear weapons, so if they attack at all it'll be nuclear). Even a country that had only conventional weapons would likely have little to lose by launching as many conventional strikes as possible if they believed that a nuclear strike was imminent anyway.

Finally, you also need to consider actions like an opponent stealing, disabling, or destroying their nuclear weapons by non-nuclear means. Without a sufficient conventional military to protect the nuclear weapons, that could be easier than you'd think. What's to prevent a foreign nation from staging a middle-of-the-night ambush to take over the weapons site?

Answer 3

There is no such thing as an nukes-only military forces.

One needs a small army just to guard the nukes against someone else sabotaging them or, worse, abusing them in some way. Nukes also don't just appear out of thin air, they need a whole industry to create and maintain them. This industry is profoundly entangled with military structures as well.

In periods of deteriorating economy and/or internal conflicts (these inevitably touch the military forces), some countries struggle with keeping their nukes safe (see Russia in 90's) or outright give up on having nukes (Ukraine in 90's)

That's why one can have nukes only after having more or less adequate "conventional" army forces.

Then again, there is a whole specter of military tasks where no single state actor may be designated as an enemy. What about a powerful terrorist group (it may as well be home-grown)?

One can always create stronger police forces, but they will be an army in any aspect other than the name.

Answer 4

The bulk of the problem isn't deterrence but how you use them in such a way that you suffer no consequences.

Let's say that China launches a full strike on the US and the US just shrugs and takes it on the chin. The US is gone, a nuclear wasteland. So China wins, right?

All those nukes blowing up in midair (air burst) will release lots of dust. Some of it will be the nuclear material, but a lot of it will be common dust. Add in all the nuclear fires after your strike is over and you're looking at a ton of material ejected into the atmosphere. Assuming the nuclear material doesn't make it worldwide (and that's a huge if), the dust will, and it will be devastating

In that extreme scenario, the researchers write, a cloud of black soot could envelop the sky, causing temperatures to fall dramatically. Key agricultural hotspots would lose the ability to grow crops, triggering a global famine.

"It would be instant climate change," Alan Robock, an author of the study, told Business Insider. "Nothing like this in history, since civilization was developed, has happened."

In other words, that strike would wipe out China's foe... and then China would have to suffer with the resultant climate change. It would be the penultimate pyrric victory.

Answer 5

The other answers have explained that the problem with conventional nuclear weapons is the step up of "going nuclear" being disproportionate. However, nuclear weapons need not be high powered.

In the case of Japan, low and high power nuclear weapons alone would probably not be a sufficient independent defence, because the seas are a significant resource, notably for food, along with a small land area not able to sustain tit-for-tat attacks that are described below. Theoretically if your country was large enough, then low level nuclear tactics could provide a deterrent. The demonstration of the ability, and willingness, to perform low-level nuclear attacks on enemy countries could be sufficient deterrent to prevent attack.

At their lowest power, nuclear weapons can target individuals/families: for example a Russian dissident was poisoned with nuclear materials smuggled into London. These could be delivered by agents, and/or by proxies, such as domestic terrorists.

Larger levels of nuclear contaminants can be used to poison food/water sources, fuel distribution networks, places of cultural/religious/ecological significance, or urban areas. Dirty bombs with varying levels of radioactive contaminants could delivered by agents or by rockets.

EDIT: As I have already mentioned, and commentators didn't understand, these tactics would not be effective for a country with a small land area because of the inability to sustain tit-for-tat exchanges which I foresaw might result when the origin of attacks was discovered, another thing the commentators misunderstood. Indeed the origin of these measures used for defence would be immediately obvious since they would be deployed as retaliation for a previous attack. There has been no military retaliation for the Russian poisonings on British soil. That is because Britain realizes it would come off worse in tit-for-tat exchanges with Russia.

Considering defence only, it is possible to conceive of a large country with sufficient resources being able to conduct its defence with low and high powered nuclear weapons. The threat of low level nuclear contaminants landing on enemy soil would be sufficient deterrent to attackers. In the light of one comment I have removed the part of my answer about fomenting dissent because, as one commenter quite rightly noted, the key concept of defence is having graduated deterrent response to attack.

Answer 6

If the only way you have to respond to an attack is nuclear weapons then you have no options available in how you respond to an attack this leads to a number of very critical flaws in your defensive plans

If you have no conventional military forces that means you have no submarine fleet or airforce, so the only way to deploy is via ICBM. What happens if your enemy finds a way to shoot down ICBMs reliably?

How do you react to an attack that occurs within your own cities? If an enemy manages to sneak a small force into your capital and attacks your government buildings are you going to nuke your own people to stop them?

Also conventional military have other uses such as in emergency relief where having a large body of disciplined personnel with equipment and supplies ready to go at a moments notice can save lives