In the 1950's Korean War, the USA + 16 of her allies combined, almost conpletely overran North Korea.
Until China made a direct military intervention, and pushed the USA and her allies completely out of North Korea.
At that point, a desperate and retreating General McArthur, even threatened to nuke China.
And that is the story of why we decided to get thermonuclear weapons for ourselves.
This story is repeating with Iran. America has been threatening to attack Iran for decades, and has occupied the country on their right (Afghanistan), as well as the country on their left (Iraq).
Who in their position would NOT want nuclear weapons?