The strongest sign an attack is coming that I know of is firm evidence that Russia or China is evacuating her cities.
Another sign that would get me to flee immediately (to a rural area of the US: I would not try to leave the country) is a threat by Moscow that Moscow will launch an attack unless Washington takes action A (or stops engaging in activity B) before specific time T.
Perhaps we should brainstorm leading indicators of nuclear attack.
The strongest sign an attack is coming that I know of is firm evidence that Russia or China is evacuating her cities.
Another sign that would get me to flee immediately (to a rural area of the US: I would not try to leave the country) is a threat by Moscow that Moscow will launch an attack unless Washington takes action A (or stops engaging in activity B) before specific time T.
In other words, what Putin has already been doing more and more, but with a specific deadline attached?
With a specific deadline and a specific threat of a nuclear attack on the US.