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Japan’s policy has always been to keep highly enriched uranium on hand, which they could use to make nukes in relatively short order. It’s a backup plan in case

Japan’s policy has always been to keep highly enriched uranium on hand, which they could use to make nukes in relatively short order. It’s a backup plan in case America stops being the guarantor of Japanese safety against China.

xxpor 5y ago
Do they have the wherewithal to pull off a deliverable Teller-Ulam thermonuclear warhead, without doing any atmospheric testing? Does Japan even have SLBMs or bombers? It takes a lot more to be a credible nuclear threat than just having some U235 sitting around...
- ashtonkem 5y ago
  I can't speak to the delivery aspect, but I don't think you'd even need a Teller Ulam thermonuclear warhead to make a credible threat to a neighboring power. But the delivery aspect matters a lot, obviously.
  - xxpor 5y ago
    > Teller Ulam thermonuclear warhead to make a credible threat to a neighboring power. Granted, I haven't read a ton of analysis on this, but my guess would be that you do if you're going up against someone with their own thermonuclear bombs. If China drops some of their own thermonuclear weapons on Tokyo, what's Japan's response? Dropping a fission weapon? If they got to that level, I'm sure that would be considered an acceptable risk for China. The converse is also true. If Japan dropped the fission weapon first, they'd instantly have a bunch of thermonuclear warheads headed their way.
    - tablespoon 5y ago
      > If China drops some of their own thermonuclear weapons on Tokyo, what's Japan's response? Dropping a fission weapon? I don't think it works that way. Fission bombs are perfectly capable of leveling a city. If a city gets leveled, no one's going to shrug it off because it was done with the "wrong" kind of weapon. IIRC, modern thermonuclear warheads have yields along the lines of a couple hundred kilotons. Even through theoretically they can be made much more powerful, in practice they aren't.
- kesselvon 5y ago
  Nuclear weapons are a technology that is almost 100 years old, and is old enough for a country like North Korea to pull off. It has a space program with rockets, a nuclear power sector, etc. It's the thing you do when you want all the pieces for a potential nuclear weapons program without signaling that you're looking to develop a nuclear weapons program. I think the current contemporary estimate is that Japan could assemble a functioning nuke in 6-12 months.
  - petra 5y ago
    Isn't 6 to 12 months that ages in wartime ?
    - gruez 5y ago
      Presumably china's not randomly declaring war? They could start building it once tensions rise.
    - ashtonkem 5y ago
      The presumption is that they’d begin building them once they decide that America won’t guarantee their safety, not once China declares war.
      - PicassoCTs 5y ago
        China had a one child policy. It cant declare war. Everyone of those soldiers has two generations of parent pensioners depending on it. China is not trying to emulate the us and thus - disregarding the propaganda, not gearing up for war.
        ashtonkem 5y ago
        > It cant declare war. History tells us that countries can and do declare war when it would be illogical for them to do so. There was a running theory before WW1 that the economic interconnection of Europe made war impossible, which was obviously false. Does this mean China is gearing up for war? No. But to declare that China can’t declare war is fairly ahistorical. > China is not trying to emulate the us … disregarding the propaganda Ironically, I’d argue that this is propaganda. “We’re not like that other power, we’re so much better” is pretty classic stuff. Although I’d argue that China isn’t emulating America, I’d argue that China is emulating 19th century Britain with its debt diplomacy.
- abecedarius 5y ago
  The U.S. funded an exercise back in, iirc, the 60s of getting a few physics grad students to design a fission bomb using only open-source info. (That's far less resources than modern Japan could give it.) They succeeded at coming up with a viable implosion design.

xxpor 5y ago

Do they have the wherewithal to pull off a deliverable Teller-Ulam thermonuclear warhead, without doing any atmospheric testing? Does Japan even have SLBMs or bombers? It takes a lot more to be a credible nuclear threat than just having some U235 sitting around...

ashtonkem 5y ago
I can't speak to the delivery aspect, but I don't think you'd even need a Teller Ulam thermonuclear warhead to make a credible threat to a neighboring power. But the delivery aspect matters a lot, obviously.
- xxpor 5y ago
  > Teller Ulam thermonuclear warhead to make a credible threat to a neighboring power. Granted, I haven't read a ton of analysis on this, but my guess would be that you do if you're going up against someone with their own thermonuclear bombs. If China drops some of their own thermonuclear weapons on Tokyo, what's Japan's response? Dropping a fission weapon? If they got to that level, I'm sure that would be considered an acceptable risk for China. The converse is also true. If Japan dropped the fission weapon first, they'd instantly have a bunch of thermonuclear warheads headed their way.
  - tablespoon 5y ago
    > If China drops some of their own thermonuclear weapons on Tokyo, what's Japan's response? Dropping a fission weapon? I don't think it works that way. Fission bombs are perfectly capable of leveling a city. If a city gets leveled, no one's going to shrug it off because it was done with the "wrong" kind of weapon. IIRC, modern thermonuclear warheads have yields along the lines of a couple hundred kilotons. Even through theoretically they can be made much more powerful, in practice they aren't.
kesselvon 5y ago
Nuclear weapons are a technology that is almost 100 years old, and is old enough for a country like North Korea to pull off. It has a space program with rockets, a nuclear power sector, etc. It's the thing you do when you want all the pieces for a potential nuclear weapons program without signaling that you're looking to develop a nuclear weapons program. I think the current contemporary estimate is that Japan could assemble a functioning nuke in 6-12 months.
- petra 5y ago
  Isn't 6 to 12 months that ages in wartime ?
  - gruez 5y ago
    Presumably china's not randomly declaring war? They could start building it once tensions rise.
  - ashtonkem 5y ago
    The presumption is that they’d begin building them once they decide that America won’t guarantee their safety, not once China declares war.
    - PicassoCTs 5y ago
      China had a one child policy. It cant declare war. Everyone of those soldiers has two generations of parent pensioners depending on it. China is not trying to emulate the us and thus - disregarding the propaganda, not gearing up for war.
      - ashtonkem 5y ago
        > It cant declare war. History tells us that countries can and do declare war when it would be illogical for them to do so. There was a running theory before WW1 that the economic interconnection of Europe made war impossible, which was obviously false. Does this mean China is gearing up for war? No. But to declare that China can’t declare war is fairly ahistorical. > China is not trying to emulate the us … disregarding the propaganda Ironically, I’d argue that this is propaganda. “We’re not like that other power, we’re so much better” is pretty classic stuff. Although I’d argue that China isn’t emulating America, I’d argue that China is emulating 19th century Britain with its debt diplomacy.
abecedarius 5y ago
The U.S. funded an exercise back in, iirc, the 60s of getting a few physics grad students to design a fission bomb using only open-source info. (That's far less resources than modern Japan could give it.) They succeeded at coming up with a viable implosion design.