Having less nukes is not the same as disarmament it's not even comparable. They dropped two nukes and did that much destruction in Japan, 2, and those were 1940s nukes, even with this change the US would still have thousands of nukes.

https://www.scientificamerican.com/article/how-many-nuclear-weapons-exist-and-who-has-them/

the United States admits to having 5,550

Ukraine went to 0 nukes, the US has 5000+ nukes, how would that even be comparable if the US let's say went down to 1000 nukes. That's still 1000 nukes more than 0.

Nukes wouldn't have saved them from being couped