Si non potes reperire Berolini in tabula, ludens essetis non WIF.
Hey, get your stinking cursor off my face! I got nukes, you know.
If it (the US) attempts declarations of war against both Germany and Italy in the same step, resolve it as one attempt, rather than one for each. If the attempt succeeds, it would count as 2 declarations for US entry purposes (see 13.3.2).
So it's the US player's option. Usually, the US will DOW both Germany and Italy on the same attempt - but not required to.