Both local development of a nuke and the receipt of a nuke by other means will resolve Yes. A nuke that legally belongs to another country but is consensually stored and ready to use in the territory or on weapons platforms belonging to a new country will resolve Yes, as will any other new or revealed nuke-sharing.
So if the Cuban Missile Crisis happened tomorrow, Cuba would resolve Yes. The same for the First Taiwan Straight Crisis. Likewise, Canada being revealed to secretly keep US-owned nukes in their territory would resolve Yes even though they were previously denied. Past shared weapons do not count.
When there is ambiguity as to whether a country actually has nukes or not, non-proliferation groups will be given priority as to their opinion. If you add a country, please check that they are not already widely understood to currently have or host nukes.
Update 2025-02-03 (PST) (AI summary of creator comment): Important Clarification:
Being nuked (i.e. a country being attacked with a nuclear weapon) does not count as coming into possession of a nuclear weapon, even if it is only temporary.
1,000@JoshuaWilkes Edited it to say N/A but I don’t think early partial N/A is a thing for this kind of market. Obviously based on the description it’s invalid.
@JoshuaWilkes Well I can't N/A without getting mods, and it's a mini market from before the pivot, so I may just let people who don't read the description spend 10 mana on it.