[crapshoot101]

Japan may not officially have nuclear weapons, but they do not lack the capability - if they decided to weaponize (which would never happen short of a Chinese existential threat), they could do so in a matters of days, not months - the nuclear knowhow is clearly there.

The rest of your point is fair - for Japan to go to war would take a fundamental shift in the country, and its questionable whether the Senkaku Islands would meet that level. China is an aggressive, scary power in a lot of ways, and we ought to be cognizant of the dangers it poses - and the Japanese (and the Vietnamese, and the Phillipinos) are.

[vilhelm_s]

"Days" seems way too short. I Googled a bit, and the pages that came up (see below) suggest between 6 months and 10 years.

The estimates vary depending on how many and what kind of weapons they would build. Apparently Japan has a small stockpile of weapon-grade plutonium, and a huge stockpile of less refined plutonium. So they could build a small number of bombs quickly (the 6 month estimate), but building more would require either designing the weapon around less refined plutonium (which increases the risk that it would not work) or building a refinement plant (several years). They would also need some way to deliver the weapons---the most difficult option is ballistic missiles, which gives the 10-year estimate, while cruise missiles on submarines would be faster.

http://dspace.mit.edu/handle/1721.1/85865 (see footnote 35 on page 11)

http://thediplomat.com/2012/10/japan-joining-the-nuclear-wea...

http://muse.jhu.edu/journals/washington_quarterly/v026/26.1k...

[Dylan16807]

How about the traditional nuclear bombing method of a plane?

[vilhelm_s]

The second link says

> A nuclear triad — land- and sea-based missiles combined with weapons delivered by manned bombers — holds little promise in light of Japan's lack of geographic depth and the vulnerability of surface ships and aircraft to enemy action. That means fielding an undersea deterrent would be Tokyo's best nuclear option.

[ekianjo]

> Japan may not officially have nuclear weapons, but they do not lack the capability - if they decided to weaponize (which would never happen short of a Chinese existential threat), they could do so in a matters of days, not months - the nuclear knowhow is clearly there.

You don't make nuclear weapons in days. Unless you have no idea what you are talking about. Weapon grade uranium takes months to produce. Why do you think Iran has been trying for so long to make such material ?

[Symmetry]

I think you're underestimating how long it takes to separate U238 from U235 or breed plutonium.

[mchouza]

Japan has more than 1000 kg of HEU: http://www.nti.org/analysis/articles/civilian-heu-japan/

[Symmetry]

Ok then. With that and since they've almost certainly designed a device and worked out the logistics just in case I'm quite willing to believe they could get a number of boosted fission devices assembled in less than a month.

[ianburrell]

Japan has one of the worlds largest stockpiles of plutonium. Nine tons stored at home, and thiry five tons stored in Europe waiting to be reprocessed into MOX fuel.