The US is one of the few western countries that are not a signatory to that treaty and a few other weapons/human rights related treaties. For... obvious reasons

The US is one of the few western countries that are not a signatory to that treaty and a few other weapons/human rights related treaties. For... obvious reasons. Signing a treaty when you would just be ignoring it is typically not a diplomatically smart move. Better to not sign the treaty if at all possible.