Are you implying it's a "false flag" effort? I find that unlikely.
During my life, i've talked to a bunch of conspiracy nuts, and many of them really do believe that there is this massive "Jewish Conspiracy" against America.
You can't reason with them. They weren't reasoned into their positions, and they won't be reasoned out of them.
There are antisemitics all throughout the political spectrum, but ‘the left’ will tag ‘the alt-right’ as “ALL” antisemitic - discrediting all of the alt-right (watch- Hillary will most assuredly do that Thurs)
There are far more antisemitic on the left throughout the world.