What interests me is that the US military should have known this long before December 26 of last year
US military is 1 thing & US intelligence is another thing & US R&D community is still another thing.
Same goes for all countries.
The military is just an operator of products.
The R&D community makes those products.
The Intelligence agencies spy on rest of the world. And CIA, NSA, NRO, etc must have got something, obviously they're not oblidged to share anything to public.
So the US R&D community (NASA, AFRL, LM, NG, Boeing, etc) must have anticipated potential adversaries since beginning, it is something endless. F-22 was designed in 1980s, that's 45 years till now.
Initially F-22 looked different with arrowhead shape like F-117, but was re-designed b/w July-15 & mid-October 1987, in just 3 monrhs, like said by Sherman Mullin (YF-22 project manager) in 1990s TV documentaries still available on Youtube. Check this video from 16:40 to 18:50
View: https://www.youtube.com/watch?v=oin5RnxdYJY
The point to note here is that they could redesign in 3 months in 1980s version of mainframe or super computers. Then imagine what they can do with today's computing with AI & how fast. So if they went back to drawing board after J-36 TD revealed, it is not a big deal.
Like J-20 7 J-31/35, the day China will clearly reveal J-50 (& perhaps naval version also) in closeup in air or on ground, then just like B-21 they'll reveal the NGAD & F/A-XX anytime in next few years & we'll see numerous documentries on NGAD competition, just like on ATF & JSF ones.
Artist Rodrigo Avella has made so many permutations of NGAD & F/A-XX that 1 of those or a combo will definitely fly
, bcoz real jets are not like videogame jets.