Within a few minutes various sensor system will know its trajectory. Probably one of several naval ships will fire on the missile and shoot it down.
The democrats and liberals will immediately come out and apologize for hurting the missile, and hope Trump allows Little Kimmy to try again.
The boomer sub would launch all 16 missiles 30 seconds after the bomb hit LA (or Pearl Harbor or San Diego). The second strike would be worse than the first. BUT I think—Kim will set us up, hit his own people and say it was the USA before launching—That way he could get Russia and China on his side. He’s no fool. Go to the UN as be blows South Korea off the map.
You forgot “and blame Trump for provoking Kim into taking the only action he felt he had left”.