It's credible without the citation. People are dumb / mendacious / impulsive. The more weapons, and the bigger the weapons, the greater the consequences of any dumbness, mendacity or impulse (viz the man-on-the-street's 9/12 "glass Mecca!" rants from the USA).

This risk is independent of any deterrent effect.

A weak deterrent and a high risk combine to make the possession of a deterrent more dangerous than not having it. Especially if you could have spent the billions on something more useful.