Not quite right, oh myopic and insularly minded Beagle.
(For Spams, that's the one which started in 1939.)
It started in 1937, when the Japanese invaded Manchuria.
Your insular PoV is noted, as it was noted by one Admiral Ernest King when the whinging Poms cried for a Germany first strat ...
Just a thought: if you are going to post like a cnut, standby for return fire.
From this side of the pond, in the years of, say, 1937 to 1939, a great many Americans would have been more than happy to watch the Old World kill one another off in yet another bit of intramural homicide. You should thank your lucky stars that our President, FDR, was not one of them, and that he took a longer view.
Instead, you piss and moan. This helps us Yanks understand where the Australians coined a term something like "Whinging Pom."
"Has not communication been the weak point of all military operations since time began?"
Yes. As Napoleon is said to have hollered ... "Where is Grouchy?"
Insofar as JTIDS ... well, when I was in theater a few years back, it worked pretty well providing you had the kit and crypto at hand. Let's say it helped put a bit of iron on target.
It ain't perfect, but it has been improving a bit.
Blue on blue is still a risk.