But it doesn't change anything. The "plenty of warnings" were essentially nothing that McArthur or JCS were convinced by. If they even saw the "intercepts" intel at all, they probably wanted aerial confirmation. The JCS instructions were clear, to hold up if there were a real threat. Instead, the Chinese went for the sneak attack from behind the lines coming down from their pre-positioned North Koreanmountain hideouts, rather than an open crossing of the Yalu. All movements had been done at night.
If we had better surveillance then, we would have spotted them, and our bombers would have had a field day while they were relatively immobile. They would have been annhilated, even with our puny forces on the ground.
But such an tactical operational requirement did not in fact warrant the secrecy if they strategically merely wanted us to hold up...they simply had to OPENLY make clear they were serious. Our chicken-shit marching orders would have forced a pull-back.
The main factor in deterrence is credibility.
It means that McArthur and JCS were not very smart.
The main factor in deterrence is credibility.
So the Chicoms got it. Next time they issue a subtle warning they will be taken seriously.