Really?
If it's moving and not on the beam, it's a simple radar target. If it beams or slows down it's a more difficult radar target, but that's just the use of different modes and operator skill.
Oh, and despite the camouflage, they are not invisible.
As for kill, IR missile or gun. Nice big, slow target, can't chage its velocity vector too quickly (understand that the vector is pretty short- it can be moved, but for defeating a tracking solution, not enough). Yum.
[awaiting manoeuvrability comments with glee]