Small point but this isn't exactly true, especially among US policymakers and media people. All you need to do here is read the chorus of people in official / corporate media going "nuclear war would be bad, but [...]". You can also rewind to the enormous shit-fit Washington types threw last summer when Biden pulled out of Afghanistan, or go even further back to the Iraq war.

Washington is full of chickenhawk warmongers dying to send other people's children into battle, consequences be damned. It's the rare thing that is really bipartisan, too. A lot of people's careers depend on support for World War III, so they find a way to be okay with it.