Well I am not convinced Biden would even launch on alert as I think he and the toads around him would surrender first...
According to Annie Jacobsen, launch on warning is evil and we should accept the first strike and then thoughtfully respond as needed. And the President alone should not have the sole launch power. He should have to convince a committee of his top advisors. Totally not kidding.
She breezes over how one of the grandest battles in policy was removing launch decisions from the military command leaders and consolidating it into the White House.
Then she also mentions the role of the Chairman of the joint chiefs, and how he has no role in the launch decision. And conveniently forgets about Mark Milley who ordered any launch orders be approved by him before following during the DC coup in 2020.
If I remember correctly, Clinton issued a PDD that we would retaliate upon missile impact, rather than launch.