None of the above, actually... I doubt anyone will use a nuke in the near future, as tensions aren't high enough to risk it.
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The Iran vs US has been going on for a while & I doubt it's any worse now than it was during the time Raegan & Khomeini (I probably spelled those names wrong...). No nukes were used then...
No nukes were ever used in the Israel - Iran conflict & it's not any worse now than it was under Khomeini's rule.
On a side note, Iran doesn't have the technology (yet).
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England has nukes, but it depends on the US when it comes to military actions (the last time they waged a war by themselves was against Argentina (the falklands war)), so the chances they'll ever use one is close to non existant (they will say that it's a fantastic, superb action when the US launches one, but that's an entirely different story)...
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France has nukes, even tests them, but is not at war with anyone at the moment, so there's no need for them to use nukes...
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Israel has nukes, but doesn't need them. They have a powerful army and can use that when threatened by another country. The only enemy they face are terrorists who live amongst their own people and I really doubt they'll nuke their own just to get rid of some terrorists
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Pakistan & India have been at eachother's throats for ages, but ever since both countries have nukes, relations actually seem to have been improving (slightly). Now they're actually talking with eachother. Besides, both countries know that if one uses nuclear weapons, they'll be nuked themselves.
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Russia and China are currently not at war with anyone, except with people living 'within their own borders' (read Taiwan, Tibet, Chechenia). Nukes aren't going to help submit them.
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What remains are North-Korea and the US. However, it's still not certain North-Korea has nukes and even though there's 100% certainty that the US has them, they have no enemies dangerous enough to warrant the use of nukes. The enemies that the US has cannot be nuked because they have no allegiance with the countries they're hiding in (& you can't just nuke some terrorists without harming the innocent people also living in the country) and are constantly on the move...