Pardon my ignorance, but...
Why would the PLAAF ever attempt to fly the J-20 undetected within range of Japanese radar during peace time? All they would be doing is giving Japan opportunities to gather free intel. I'm sure PLAAF would love for the USAF to fly the B-21 off the coast of China so they can conveniently gather signals intelligence off the B-21.
I would think that stealth fighters like the J-20 and F-35 would always use radar reflectors when flying over international territory.
Why would the PLAAF ever attempt to fly the J-20 undetected within range of Japanese radar during peace time? All they would be doing is giving Japan opportunities to gather free intel. I'm sure PLAAF would love for the USAF to fly the B-21 off the coast of China so they can conveniently gather signals intelligence off the B-21.
I would think that stealth fighters like the J-20 and F-35 would always use radar reflectors when flying over international territory.