There's nothing quite as stealthy as a target that is on the other side of 50 million tons of rock. (Universally available and cheap terrain data, and computer processing/memory improvements, have done wonders for the flexibility of terrain/imagery referenced navigation.) And quite simple LO measures like a flat top and inlets concealed under the wings and body can give the best AEW&C a hard time, when target is deep into the terrain clutter.
There's not a lot of good, active defense. although the Russians and Chinese both use gun/missile Shorads to protect relocatables. The best bet is to rely less on fixed facilities, the counter to which is adding more smarts (even a datalink) to the missile.
On the other hand - if you're going in to stooge around in your 5genTM Wunderwaffe, looking for S-400s and TELs inside the red bubble, you need to make sure that your signature allows you to do that. X-band dominated bowtie may cut it. It may not. Don't want to find out which, the wrong way.
TPY-2 is a very powerful X-band radar that looks up in the sky for inbound ballistic missiles. over a fixed sector. Not a lot of good for air defense.