A third of the US has become convinced that if they don't brutally deport millions of undocumented immigrants (who have been painted as horrible criminals), their way of life will be destroyed.
You think it would be so difficult to convince those people of the righteousness of dropping nukes on one of those "shithole" countries if they were already convinced that those people presented an existential threat?
People were convinced to invade Iraq on a lie about WMDs.
Most Americans think nuking Hiroshima and Nagasaki was the right thing to do.
I don't think it's difficult to imagine them agreeing to drop nukes to "save America".
Speaking of Iraq, Sadam decided against using chemical weapons in the Gulf War because he had received intelligence from the Russians that the Americans would counter with nuclear weapons and he didn't want to risk that.