1. Nobody would launch nukes domestically, so moot point.
2. Using nukes internationally would be a faux-pas beyond fixing. Every modern, nuclear-equipped nation understands this.
3. The United States doesn't need nuclear weaponry to dispel invaders, or even to retaliate against foreign attacks. Their nuclear weapons exist to deter other nuclear superpowers from using their weapons for petty gain.
You're free to argue that DU rounds are effectively a poisonous weapon and should be banned on those grounds. I would agree. That doesn't change the fact that depleted uranium is not a nuclear weapon.
Yes? What about their nuclear policy from the past half-century convinces you otherwise?