Optical tracking. It is what took down O'Grady in Bosnia. Stealth reduces the Radar cross-section, thus reducing the possibility of EW Radars to detect. Once a TTR finds you, no current amount of stealth tech can defeat it. Radar absorbing materials help reduce detection and can quite possibly break a TTR lock but it is quite difficult and the F-117 could not maneuver to break a lock. The newer F-35's are built to maneuver so they might be able to. Hope their RAWR gear is current.
Don’t need TTR with certain missiles, detect with search and launch and the missile does the work. . .flies out most of the way then “opens” it eyes (TTR) just prior to impact.
Cool stuff.
Yup, the JSF has made a lot of promises but I’ll withhold judgment on that platform.