Semi.
It's greatest stealth feature is the ability to fly at Mach1 at 300ft.
Nothing else can do that.
True, but the radar cross section is significantly reduced from what it should be. Not enough to be a true stealthy aircraft, but enough that it won’t be seen coming a couple hundred miles out like, say, the Bear or our own B-52.
I’m sure an f-15 can pull that off. Air is dense there, but the f-15 pushes a lot of power out. I’m not 100% sure though, I’ve never heard about it. I just know that thing has so much power, you can stand it on end on the ground and it will accelerate straight up.