Disclaimer: I apologize if this has been discussed earlier. Could not find the exact scenario I was thinking with search.
Scenario as follows:
After USA joining the WW2, Germany realizes that obviously it is not going to be good, so that something must be done. They decide to mount a surprise strike to some US east coast cities (New York/Washington/Portland/Boston) with limited amount of long-range bombers. This is not to cause much damage, more like in way of the Doolittle raid, to have a moral effort and to tell the enemy that they are not safe.
This will happen late 1942 or 1943, using Me.264 or Ju.390 planes (can suggest others but I think these are the only ones with range for return). As such, this would be with small bombload, maybe 1000 - 1500kg per plane, and would be directed towards port installations or governmental buildings. Also, the amount of planes will be something like 10-20.
They would probably need a few subs or ships as radio beacons for navigating aid. This works a bit under assumption that this plan is not revealed to allies through Enigma/Bletchley Park and Luftwaffe can at least obtain a surprise until they take off (meaning that allies do not have knowledge of such operation being undertaken)
Thoughts? I think this would slow down the allied effort and make them do some more considerations, like building a air-defence and radar network in US east coast (As I understood there was not much at that time, correct me if I am wrong). Also as such, I think that one or two this kind of raids in short time could succeed, after that the element of surprise would be lost and air-defence network would catch up.
Also I think that for initial raids, the bombers would be nearly impossible to catch unless there would be a CAP in near vicinity. The mission profile used would be bit like with the "Steinbock" -raids, giving the bombers a good escape velocity.