A lot of false premises and false assumptions in that statement. We haven't arrived at a conclusion that "fighting" is the answer, or that our opposition will be 1.5 billion if we chose to fight, or if their numbers will be the deciding factor should a fight be inevitable.
I'm sorta thinking we maybe should focus on keeping them out of our territory, and not helping them gain power in their own territory. Things like allowing Iran to arm itself with Nukes is about the most brain dead stupid thing this nation can do.
Hitler in the Sudetenland? People said we should have stopped him then. Hitler didn't have Nuke ICBMs. To quote Yogi Berra, "it's like Deja Vu all over again."
How about you settle down and discuss this issue rationally instead of going all emotional on us?
Personally I want to know how we 'have to fight' 1.5 billion anyone to begin with. AFAIK, we are on the opposite side of the planet as 1.5 billion Muslims. The only ones we HAVE to fight are the ones already here when they go Jihadi.
Now the only way that number increases if, say, some bleeding heart liberal works to import more of them. Since they have no navy capable of transporting multiple Normandy level invasions, they have to rely on cruise ships and commercial airlines.
And those require passport/Visas.
Seems to me, as usual, the biggest threat to America comes from within. Leftist enablers. Simple math really.