Well, let's think about this... How is the incredible rise in anti-jewish sentiments and actions, such as vandalizing and burning of jewish cemeteries, calling for jewish genocide on American colleges and an endless number of similar things — anti-zionism? It's not, but it's too much for some people to admit that they hate jews so they claim to hate zionists.
During Stalin's final years, there was a campaign targeting jews, only the were referred to as "cosmopolites", this way you could call for jewish genocide without having to say it, 'cause you know...
Is it possible to criticize Israel and not be antisemitic? Sure thing — but that is not at all what's happening today, otherwise jews, who are not Israelis wouldn't feel more unsafe than usual this past month+.