Let's say that you are the US President.
A full-scale Russian nuclear launch against the continental USA has been confirmed (you don't know how and you don't know why). Thousands of nukes have been launched against the USA; you can only intercept maybe 10% of them. In 20 mins, the USA will be no more.
Your generals say to you:
"Mr. President. The Russian launch is confirmed. They're going to destroy our whole country, so let's hit them back with everything we've got."
So the discussion question is... in such a situation:
1. Do you give the authorisation for a full nuclear strike against Russia?
2. What are your responsibilities as the US President at this point?
3. What is the objectively moral thing to do?
If you read a Cold War manual or look over the security guidelines, the Correct Answer as President is to authorise the nuking of Russia. They nuked us, so we nuke them. We die... so they die with us. Anything else is simply unpatriotic.
But I invite you to explore the issue at a deeper level. After all, at this point, it is 100% guaranteed that the USA is no more (that 365 million people will die and North America will be uninhabitable)... that is HORRIBLE. However, does that guaranteed fact make it ETHICAL to press a few buttons and make 144+ million more people die?
In a complete vacuum, if I said "Hey lets kill 144 million people" you would shake your head in disbelief. So what has changed to make it suddenly acceptable when you know 365 million people are going to die in 20 mins? Its certainly not self-defence. Nuking them doesn't change the fact that you're dead yourself.
Perhaps your obligations as the US President (you'd be known as one hell of a cowardly president if you didn't nuke back)? Perhaps an eye for an eye as an operational principle?
Think about it and please enlighten us.