I see not even you are willing to look into the quagmire of that thread, to extract an answer.
You also need to understand completely, that the FAQ changes like underwear, one minute it’s this way, the next minute it’s alpha this, beta that.
The latest inclination is that an UNPROVOKED attack on the U.K. / DEI brings the U.S>A. into the war. Mantlefan is right.
Before I believe it was just a declaration of war that would suffice.