North Korea has pulled off a very neat trick by during the era of superpower nuclear MAD (mutually assured destruction) detente accomplishing the same ends with conventional artillery pieces.
At the heart of any hesitancy to deal militarily with North Korea is not concern over nuclear weapons and ICBMs but the intractable problem of reportedly
thousands of artillery pieces lining the border and ready to rain explosives all over a large portion of South Korea...and the South Koreans' understandable reluctance to be bykill in a personal spat between Kim and Trump. They're far less concerned with whether foreign countries can or can not shoot down North Korean ICBMs than they are with the fact there's no way to stop the artillery shells headed
their way.
View attachment 25544
How North Korea Would Retaliate - Stratfor Worldview
This is an
excellent point and I realize that I was a bit lazy in my wording. What I was thinking but failed to express was that if the hermit kingdom intended to cause damage and wreak havoc--in the way that groups that employ terrorist tactics do--they would be better served employing those same guerrilla tactics, and carrying them out anonymously, as to cause maximum confusion. It would be truly delusional to think they could actually survive an open, direct conflict; and if they really were that delusional, they probably would have already carried out such an attack.
The artillery pointed at South Korea serves the same purpose for which we thought we were stockpiling nuclear warheads: as a deterrent. They may not be able to reach the US for "mutually assured destruction," but they can inflict a lot of damage on their neighbors to the south, our allies. I used to live in Seoul, and visited the DMZ. I'm aware of the dangers posed by North Korean artillery, but I also have noted the relatively casual attitude the South Koreans have toward their perpetual war, particularly at times when the western media is getting whipped up into a frenzy over impending hostilities that never come.
I'm not sure if the president understands any of this, which makes him vulnerable to the fallacies that lead us to the sense that a first strike is our only option. He's also likely to think that he wouldn't be responsible for the damage caused by launching a first strike, or the ensuing retaliation. This is a dangerous path we find ourselves on, and I can only hope that his advisors reign him in or even turn to the 25th amendment should he decide on a lark to make use of the nuclear football over his petty spat with another dictator.
I wish the OP had read the article I hunted up for him; it may have helped alleviate his concerns over ICBMs deploying chemical weapons over Japan. (Did anybody read the article?)
I feel bad because I didn't... but since I have a minute and I need some translation practice... yay for learning new military terms.
original article said:
弾道弾による化学兵器攻撃の脅威はどの程度だろうか？
北朝鮮情勢が緊迫している。米国は北に圧力を掛けており、北朝鮮も反発している。トランプ政権がシリアに攻撃を実施したことから、無根拠な噂だが月末に米軍が攻撃するといった話も出ている。
その中で、北朝鮮による日本への化学兵器攻撃の話題も上がっている。これは国会での質疑でなされたものだ。首相は「サリンを［弾道弾の］弾頭に付けて、この着弾させる能力については、この北朝鮮は既に保有している可能性がある」（ママ）と述べている。
だが、弾道弾への化学兵器搭載は考えがたい。なぜなら化学兵器と弾道弾との相性は悪いためだ。そもそも化学兵器は威力不完全であり、効果的な散布が難しく、戦略兵器としての用途に向かない。
不安を煽る効果は高いが、攻撃側からすれば期待できる実害は小さい。その点でまず使うものではない。
■威力が小さい
北朝鮮は化学弾頭攻撃を使用しない。
なぜなら都市攻撃には威力不十分だからだ。そもそも化学兵器は屋外での威力は小さい。散布しても雨が降っていれば洗い流され、日中であれば上昇気流で上空に拡散して威力を失い、あるいは土中に染み込んで不活性化する。その上、今日の高気密建築物には通用しない。窓を締めて空調を止めていれば一般住宅でも耐久されてしまうからだ。
ちなみに、これは戦前から判明していたことだ。毒ガス空襲が警戒されていたが、スキマだらけの和風家屋でも窓や障子を締め切り、奥の部屋にいれば耐えられることが判明。紙で目張りをすればほぼ大丈夫といった結論に達している。
さらに人口希薄な郊外や農村部に打ち込んでも効果は全く見込めない。屋外に人がいなければ効果も見込めないからだ。
この点で毒ガス攻撃はその印象ほど威力はない。
■散布が難しい
また、弾道弾では化学剤の効果的な散布も難しい。この点でも搭載は考え難い。炸裂時の散布にムラが多く蒸散や上昇気流による拡散損が多く、効果的ではないためだ。
化学兵器を効率的に使うには、目標地域に対して低めに、平均的に散布しなければならない。一部だけ高密度に散布しても無駄、上空に拡散させても無駄だからだ。本来なら地上風上からの直接散布や航空機からのガス雨下が望ましい。せめては小口径砲弾・爆弾を広くバラまく形となる。
だが、弾頭弾にはそれができない。単弾頭に50kgを詰め込んで空中・地上で炸裂させても相当量が上方に飛散し、それ以外も上昇気流で失われてしまう。さらに爆心部だけがやたらと高濃度となり、それ以外の場所を低濃度としてしまうからだ。
そもそも50㎏のサリンを炸裂させても大面積を危害できない。毒ガスとしてのサリン致死量は12ppm（半数致死量：1分間暴露）である。つまり大気1立法メートルに0.75gである。この数字だけを見れば広い範囲を危険域にできるようにも見えるだろう。だが、ムラなく均等に拡散させても縦横高さ40mづつ、球体状なら半径25mが致死圏にできるだけだ。実際にはロスがある。9割程度が無駄になれば、縦横高さ20mあるいは半径13mの範囲しか致死圏にできない。
ちなみに、実際に弾道弾で化学兵器を使う場合にはクラスター爆弾式に子弾頭でバラまく。だが、それでもあまり効率はあがらない。仮に六角柱で密に充填しても、今度は子弾頭の容積が弾殻や信管・炸薬で食われてしまい化学剤が入らないからだ。
■戦略兵器として使いにくい
最後が戦略兵器として使い勝手が悪すぎることだ。
なによりも化学兵器は少威力の割に悪評が大きすぎ、大規模な報復を招く。この点で割に合わない。
イメージほどの大量殺戮効果は期待できない。対策を講じられればほとんど無効力となってしまう。化学兵器の種類や天候、除染措置次第だが、実効としてはその土地がしばらく使えなくなる程度だ。この点で核兵器とは異なる。
だが、明らかに名目は大量破壊兵器の使用となる。世論の反応は通常弾頭攻撃とは大きく異なる。人道への挑戦として受け取られ、大規模報復も許容してしまう。
これはシリアの化学兵器使用を見ても明らかだ。直接交戦関係にない米国が「化学兵器使用は許さない」とシリア政府をトマホークで攻撃した。本来なら、なぜシリア国内の虐殺行為で米国がシリア政府を直接攻撃するのかわからないが、それは許容される雰囲気にある。
つまりは、化学弾頭弾道弾は見た目ほどには使えない兵器だということだ。使えるにしても限定的な抑止である。核兵器を持たない国が「相手が核を使えばこちらは化学兵器を使う」、あるいは冷戦中の西側のように「東側が化学兵器を使えば、こちらも使う」といった程度のものだ。
そのような兵器を北朝鮮が使うだろうか？
まずは使わない。弾道弾攻撃ならまず通常弾頭を使う。いよいよ体制が滅ぼされる間際になれば核を使う。そこに化学弾頭を使う段階はない。強いて使い時とすれば、核攻撃のついでに発射しておく程度のものだ。
注）筆者は大湊での旧軍遺棄化学弾調査に2年、化学兵器防護に2年従事した。
My translation (some liberties taken):
To what extent is the actual threat of chemical weapons being delivered with ballistic missiles?
The situation with North Korea is tense. America is putting increasing pressure on them and they are pushing back. Since the Trump administration has gone on the offensive in Syria, baseless rumors have circulated that they would attack by the end of the month. (contributing to said tension).
As such, the threat of North Korea's possible use of chemical weapons against Japan has become a topic of conjecture, even in parliament itself. In regards to their possible capacity for using ballistic missiles with sarin gas in their warheads, the prime minister expressed that North Korea might already be in possession of such weapons.
However, let's think for a minute about this, because the combination of chemical agents and ballistic missiles does not make an effective weapon. To start, chemical weapons in themselves are not as destructive, and this means of delivery limits the spread of the agent, making it a poor strategic weapon. Although it is an effective psychological weapon, as far as effectiveness is concerned, outside of the immediate blast zone the damages are relatively small. That alone makes it an unlikely means of attack.
North Korea will not be using chemical-tipped warheads, because it does not have enough destructive power when leveled against a city. Firstly, the relative power of these weapons is small when used outdoors. Even if the agent goes airborne, it can be rendered ineffective by rains, and if used during the day, the thermal updraft would send it skyward, or if it penetrates the ground it would lose its effectiveness. On top of that, modern buildings are well-sealed, and a standard modern home would be able to withstand a chemical attack by simply closing the windows and turning off the AC/closing the vents.
At any rate, this is a fact from the pre-war days, when we were vigilant against poison gas air raids: it was proven that even in the unsealed airy homes of yesteryear, by closing the windows and shoji screens and retreating to the inner room, the paper with some weather stripping would be enough to protect its inhabitants.
Furthermore, in areas with lower population density like suburbs and farmland we can anticipate little relative damage. If released outdoors where there are no people, will see even less effectiveness. For these reasons, the looming threat of a poison gas attack is not very compelling.
Dispersion is a Challenge:
Also the use of an explosive warhead makes spreading the agent difficult, which makes it difficult to imagine it being seriously developed and deployed. The irregularity of the explosion itself, along with the thermal updraft would create obstacles to effective spread.
To effectively use chemical weaponry, it must be spread evenly over the target area. A small area of high concentration is a waste, as is an attack that explodes too high in the air. By all rights the desired means of delivery would either be immediate dispersion above ground or rained down from an aircraft. If explosions are to be used, it would need to be a plurality of small caliber shells spread over a wide area.
But, ballistic missiles can't do that. By definition, they could only deliver a payload of 50 kilograms through the air and detonate above ground; anything beyond that would just get swept up into the atmosphere. The dispersion would only be concentrated under ground zero, and wouldn't likely disperse to the surrounding areas.
50kg of sarin gas, released by an explosion, is not able to inflict damage on a large area. A lethal dose of sarin amounts to 12ppm, and it would take a minute of exposure at half that dosage to be fatal. In the atmosphere, that would amount to about 0.75g per meter (from the dispersion point?). Just looking at the numbers, it seems like it would be possible to affect a large area. But even if that amount is spread evenly it would only be able to affect an area of 40m, or a spherical area with a lethal radius of 25m. There is a loss of the effective area, resulting in an actual lethal zone with only a 13m radius.
The most realistic use of chemical weapons on a ballistic missile would be to use it to spread cluster bombs, but even that wouldn't really increase the efficacy much. Even if you tried to pack them into a tight hexagonal prism, the explosives and other parts would eat up too much space, and there wouldn't even be room in the warhead.
Difficult to use as strategic arms:
Lastly, it just doesn't make sense to use these weapons strategically. More than anything, the use of chemical weapons is looked down upon severely, which is not offset by their limited efficacy, and invites massive retaliation in response to their use.
For all these reasons, chemical weapons just don't have the power to effect the mass slaughter we might imagine. A prepared target could almost completely escape major damage. It depends on the cleanup efforts, but the only real effect is a temporary inability to use the land; in this sense it differs from nuclear weaponry.
However, there's a pretense of the use of weapons of mass destruction, and the public reaction to them compared to conventional explosives is huge; their use would lead to massive retaliation. This point is obvious from the events that unfolded in Syria. America wouldn't forgive the use of chemical weapons, even though they weren't directly involved in the conflict, and launched Tomahawk missiles in response. It's not clear what their true motives were in directly attacking, but they were more quickly forgiven than al-Assad's government.
In brief, the use of ballistic missiles with chemical warheads is incredibly unlikely. Even if they could be used, they're very limited. The only likely scenarios are countries facing an enemy with nuclear weapons when they have none, to use as a deterrent just in case, or a cold war situation where if one side were to use chemical weapons the other would respond in kind.
Given all this, does anyone actually think North Korea would use these weapons?
It's doubtful. If anything, at first, North Korea would definitely just use conventional weaponry. As they get more desperate, they'd more likely go nuclear. There's no step in there for chemical weapons to be deployed. At the point that they'd use them, they would already have launched a nuclear missile.
以上
...Well, that was fun and kind of mentally taxing! I'm gonna go lay down now.
